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PRICE 25 CENTS 



ALLOY STEELS 

THEIR COMPOSITION, CHARACTERISTICS, 
STRENGTH AND HEAT-TREATMENT 

BY E. F. LAKE 




MACHINERY'S REFERENCE BOOK NO. 118 
PUBLISHED BY MACHINERY, NEW YORK 



MACHINERY'S REFERENCE BOOKS 

This book is one of a remarkably successful series of 25-cent Reference Books 
listed below. These books were originated by Machinery and comprise a complete 
working library of mechanical literature, each book covering one subject. The price 
of each book is 25 cents (one shilling) delivered anywhere in the world. 

CLASSIFIED LIST OF REFERENCE BOOKS 



GENERAL MACHINE SHOP PRACTICE 
Lathe and Planer Tools. 
Examples of Machine Shop Practice. 
Deep Hole Drilling. 
Screw Thread Cutting. 
Files and Filing. 
Principles and Practice 



No. 


7. 


No. 


10. 


No. 


£5. 


No. 


.32. 


No. 


48. 


No. 


50. 


No. 


61. 


No. 


57. 


No. 


69. 


No. 


91. 


No. 


92. 


No. 


93. 


No. 


94. 


No. 


96. 


No. 


96. 


No. 


97. 


No. 


98. 


No. 


116. 


No. 


120. 



of Assembling 
of Assembling 



Machine Tools, Fart I. 

Principles and Practice 
Machine Tools, Part II. 

Metal Spinning, 

Machines, Tools and Methods of Auto- 
mobile Manufacture. 

Operation of Machine Tools. — The Lathe, 
Part I. 

Operation of Machine Tools. — The Lathe, 
Part II. 

Operation of Machine Tools. — Planer, 
Shaper, Slotter. 

Operation of Machine Tools. — ^Drilling Ma- 
chines. 

Operation of Machine Tools. — Boring Ma- 
chines. 

Operation of Machine Tools. — Milling Ma- 
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Operation of Machine Tools. — Milling Ma- 
chines, Part II. 

Operation of Machine Tools. — Grinding 
Machines. 

Manufacture of Steel Balls. 

Arbors and Work Holding Devices. 



TOOLMAKING 
No. 21. Measuring Tools. 
No. 31. Screw Thread Tools and Gages. 
No. 64. Gage Making and Lapping. 
No. 107. Drop Forging Dies and Die Sinking. 

HARDENING AND TEMPERING 
Hardening and Tempering. 
Heat-treatment of Steel. 



No. 


46. 


No. 


63. 


No. 


3. 


No. 


4. 


No. 


41. 


No. 


42. 


No. 


43. 



JIGS AND FIXTURES 
Drill Jigs. 
Milling Fixtures. 
Jigs and Fixtures, Part I. 
Jigs and Fixtures, Part II. 
Jigs and Fixtures, Part III. 



PUNCH AND DIE WORK 
No. 6. Punch and Die Work. 
No. 13. Blanking Dies. 
No. 26. Modern Punch and Die Construction. 

AUTOMATIC SCREW MACHINE WORK 

No.. 99. Operation of Brown & Sharpe Automatic 
Screw Machines. 

No. 100. Designing and Cutting Cams for the Au- 
tomatic Screw Machine. 



No. 101. Circular Forming and Cut-off Tools for 
Automatic Screw Machines. 

No. 102. External Cutting Tools for Automatic 
Screw Machines. 

No. 103. Internal Cutting Tools for Automatic 
Screw Machines. 

No. 104. Threading Operations on Automatic 
Screw Machines. 

No. 106. Knurling Operations on Automatic Screw 
Machines. 

No. 106. Cross Drilling, Burringtand Slotting Op- 
erations on Automatic Screw Machines. 

SHOP CALCULATIONS 

No. 18. Shop Arithmetic for the Machinist. 

No. 52. Advanced Shop Arithmetic for the Ma- 
chinist. 

No. 53. The Use of Logarithms — Complete Log- 
arithmic Tables. 

No. 54. Solution of Triangles, Part I. 

No. 55. Solution of Triangles, Part II. 

THEORETICAL MECHANICS 
No. 5. First Principles of Theoretical Mechanics. 
No. 19. Use of Formulas in Mechanics. 







GEARING 


No. 


1. 


Worm Gearing. 


No. 


15. 


Spur Gearing. 


No. 


20. 


Spiral Gearing. 


No. 


87. 


Bevel Gearing. 

GENERAL MACHINE DESIGN 


No. 


9. 


Designing and Cutting Cams. 


No. 


11. 


Bearings. 


No. 


17. 


Strength of Cylinders. 


No. 


22. 


Calculation of Elements of Machine De- 
sign. 


No. 


24. 


Examples of Calculating Designs. 


No. 


40. 


Flywheels. 


No. 


56. 


Ball Bearings. 


No. 


58. 


Helical and Elliptic Springs. 


No. 


89. 


The Theory of Shrinkage and Forced Fits. 



MACHINE TOOL DESIGN 
No. 14. Details of Machine Tool Design. 
No. 16. Machine Tool Drives. 
No. 111. Lathe Bed Design. 

No. 112. Machine Stops, Trips and Locking De- 
vices. 

CRANE DESIGN 
No. 23. Theory of Crane Design. 
No. 47. Electric Overhead Cranes. 
No. 49. Girders for Electric Overhead Cranes. 

STEAM AND GAS ENGINES 

No. 65. Formulas and Constants for Gas Engine 
Design. 



SEE INSIDE BACK COVER FOR ADDITIONAL- TITLES 



MACHINERY'S REFERENCE SERIES 

EACH NUMBER IS ONE UNIT IN A COMPLETE LIBRARY OF 

MACHINE DESIGN AND SHOP PRACTICE REVISED AND 

REPUBLISHED FROM MACHINERY 



NUMBER 118 



ALLOY STEELS 

By E^&rLAKE 



CONTENTS 

Nickel Steel - 3 

Nickel-chromium Steel _-------9 

Vanadium Steel - - - -- 17 

Manganese Steel 24 

Titanium Steel 27 

Natural Alloy Steel 38 



Copyright, 1914, The Industrial Press, Publishers of Machinekt, 
140-148 Lafayette Street, New Tork City 



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V 



MAR 30 1914 

©CI.A37039G 



CHAPTER I 



NICKEL STEEL 

Nickel steel is used to. a large extent in the construction of high- 
grade machinery, and can be purchased in the open market in almost 
any percentages of nickel up to 35 per cent, and with the carbon 
component varying between 0.10 and 1.00 per cent. Nickel was added 
to carbon steel as the result of investigations which were started for 
the purpose of overcoming the "sudden rupture" that is inherent in 
all carbon steel. This property or tendency of carbon steel to rupture 
is the subject of numerous investigations by the railroads of the 
country at the present time, owing to the many accidents that have 
occurred in the past few years due to broken rails. Nickel added to 
steel largely overcomes this tendency, and nickel steel is used suc- 
cessfully for parts of machinery that have to withstand severe 
shocks and torsion, such as the crankshafts and connecting-rods of 
internal combustion engines, propeller shafts, automobile axles, and 
other parts of a similar nature which have to withstand similar 
strains and stresses. 

If nickel is added to steel in any percentage not exceeding 8 per 
cent, the tensile strength and the elastic limit of the steel will in- 
crease with the percentage of nickel. If the percentage of nickel is 
above 8 per cent, but less than 15 per cent, its effect on the steel be- 
comes, for some reason, entirely neutralized and brittleness is pro- 
duced. If the nickel percentage, however, is above 15 per cent, then 
the strength and elasticity become practically equal to that of the 
nickel steels with percentages of nickel less than 8 per cent. If the 
nickel percentage is increased above 20 per cent, .the strength and 
elastic limit gradually decrease, but the elongation increases. 

The elongation shows a slight rise until about 3 per cent of nickel 
is added to the steel, and after that it shows a rapid decrease, until ■ 
the zone of brittleness is reached, when it becomes nil. With from 
20 to 25 per cent nickel, the elongation again rapidly rises, and from 
that point to 100 per cent it shows a slight increase. The best results, 
therefore, in steels that are used for machine parts are obtained with 
a nickel content of 3% per cent, although for some purposes 5 per 
cent nickel steel is used at a sacrifice of the elongation. 

Beneficial Effects of Nickel in Heat Treatment 
The qualities of carbon steel 'ar,o, susceptible of change by heat- 
treatment the same as are those of alloy steels, but the higher the 
carbon content is the more likely is the steel to burn and thereby 
reduce its strength, and it is extremely difficult to caseharden steels 
which contain more carbon than does mild steel without destroying 
their good qualities and strengths. By the addition of nickel the 



4 No. 118— ALLOY STEELS 

tendency to burn is largely overcome, and the susceptibility to heat- 
treatment is remarkable. This is best illustrated by Table I in which 
a nickel steel was given different degrees of hardness. Its composi- 
tion was as follows: Nickel, 3 per cent; carbon, 0.30 per cent; man- 
ganese, 0.40 per cent; phosphorus, 0.05 per cent; sulphur, 0.04 per 
cent. 

A good quality, open-hearth, 0.30 per cent carbon steel, as received 
from the mill in the untreated state, shows the same strength as the 
untreated nickel steel in Table I, but it cannot be raised to much 
more than one-half of the strength of the nickel steel in its hardest 
state, and even then it is much more liable to fracture under shock 
tests. 

Nickel increases the ability of steel to withstand shock stresses 
even though the shape be intricate and lightened with holes. When 



STRENGTH OF NICKEL STEEL AT DIFFERENT DEGREES 
OF HARDNESS 



Hardness 


Tensile 

Strength, 

Pounds per 

Square Inch 


Elastic 

Limit, 

Pounds per 

Square Inch 


Elongation 

in 2 Inches, 

Per Cent 


Reduction 
of Area, 
Per Cent 


Annealed 


88,000 
130,000 
220,000 
225,000 


60,000 
130.000 
190,000 
225,500 


28 

20 

12 

8 


58 

6 

37 

19 

Machinery 


Medium hard 

Hard 


Very hard 





properly combined with carbon, it largely removes the tendency of 
crystallization, and the steel may be casehardened without fear of 
the core being brittle. If high in carbon, however, it will not stand 
local hardening, but may be hardened in oil without difficulty. 

What the Microscope Reveals in Testing- Steels 

Steel subjected to different heat-treatments shows different proper- 
ties when examined under a microscope, and microscopy is, therefore, 
becoming one of the methods of examining and testing different 
steels. If we take a piece of steel containing less than 0.85 per cent 
of carbon, polish it, attack it with a few drops of picric acid and 
examine it under a microscope, the results will differ according to 
its composition and the treatment it has undergone. In a piece 
of steel that has been cooled slowly, small dark masses will appear 
which are more numerous the closer the carbon is to 0.85 per cent. 

Next, heat this steel to 1400 degrees F., or a dull red, and quench 
in water, then polish, attack with, picric acid, examine under the 
microscope as before, and it wfli show extremely fine lines inter- 
secting each other in the direction of the sides of an equilateral 
triangle. Therefore, it is evident that by annealing or heating and 
quenching this steel we can change its structure, and its condition 
is readily determined by the aid of a powerful microscope. 



NICKEL STEEL 5 

Other molecular changes take place in heat-treating steels and 
some of these are governed by the carbon contents. If certain steels 
are given the heat-treatments just described, the average blacksmith 
would try them with a file, and if the file bites as well as it did before 
heat-treating, he would throw the steel out as not hardened, yet 
transformations have taken place, and tests would show that the 
tensile strength and elastic limit have been raised while the elonga- 
tion and reduction of area are reduced. In the case of the nickel 
steel of which Table I shows the test, these transformations have 
caused a variation in strength from 88,000 pounds to 225,000 pounds 
per square inch; this would have been considered impossible a few 
years ago. 

TABLE II. EFFECT OF HEAT-TREATMENT ON NICKEL STEEL OF THE 
FOLLOWING COMPOSITION: 



Nickel, 2.54 Per cent; Silicon, 0.26 per cent; Carbon, 0.33 per cent; Manganese, 


0.43 per cent; Phosphorus, 0.023 per cent; 


Sulphur, 0.032 per cent 




Tensile 


Elastic 


Elonga- 


Treatment 


Strength, 


Limit, 


tion in 




Pounds 


Pounds 


2 Inches, 




per Sq. In. 


perSq. In. 


Per Cent 


Quenched at 1600° F 


225,000 

215,000 


208 000 


4 


Quenched at 1600° F., tempered at 600°. . 


201,000 


6 


Quenched at 1600° F., tempered at 800°. . 


190,000 


150,000 


9 


Quenched at 1600° F , tempered at 1000°. . 


170,000 


145,000 


12 


Quenched at 1600° F., tempered at 1200°. . 


155,000 


125,000 


14 


Quenched at 1600° F., tempered at 1400°. . 


135,000 


98,000 


17 


Quenched at 1600° F., tempered at 1600°. . 


104,000 


65,000 


24 






Machinery | 



Thus alinealing, hardening and tempering steel are resorted to 
for raising the tensile strength, elastic limit, and its ability to with- 
stand shock and torsional stresses, as well as to put a fine cutting 
edge on tool steels. \ 

Need for Annealing" 

In heat-treating steels for strength, and especially nickel steel, it 
should always be remembered that hardening by quenching produces 
internal strains which can only be removed or destroyed by temper- 
ing or drawing after quenching. Thus nickel steel cannot be used 
in its hardest state, in which it has the highest tensile strength and 
elastic limit; but the piece must be tempered, thereby reducing the 
strength and increasing the elongation in order to reduce the brittle- 
ness as well as the internal strains caused by hardening. These 
internal strains may also be caused by forging, hammering or work- 
ing, and the best results will be obtained if the steel is annealed after 
each important operation. 



Liability of Nickel Steel to Warp, Decarbonize and Crack 
Three things work to the detriment of nickel steel and should 
always be taken into consideration when hardening it. First, it nearly 



6 No. 118— ALLOY STEELS 

always warps in quenching; second, it may be decarbonized in heat- 
ing; and third, fissures and cracks might occur in quenching. There 
are several rules which can be followed to minimize the tendency of 
steel to warp in quenching. If a piece is cut from stock that has 
been subjected to some mechanical treatment, it is very liable to be 
deformed on being heated, and it is undeniable that of the deformations 
attributed to the hardening process, a large part are due to the 
heating which precedes quenching, and results from the use of metal 
which has been mechanically worked. To overcome this, the steel 
should be thoroughly annealed before it is machined to size, so that 
the metal will be in a state of repose. 

In quenching, the piece should be immersed in the bath in the 
direction of its principal axis of symmetry, so that the liquid can 
cover the greatest possible surface, and it should never be thrown 
into the bath. Thus a shaft should be immersed vertically and a gear 
wheel perpendicular to its plane. The piece should also be agitated 
in the bath so as to destroy the coating of vapor which usually forms 
around the piece and prevents its cooling rapidly. 

To reduce the tendency to decarbonize, it is necessary to provide 
against oxidation; therefore, the pieces must be prevented from 
coming in contact with the gases. This can be done by placing the 
pieces in a protecting retort, or by using a metallic heating bath, 
such as lead. 

Fissures or cracks which occur in hardening are caused by the dif- 
ferent parts of the piece cooling unevenly, thus producing internal 
stresses of enormous proportions. These fissures may be prevented 
by reducing the rate of cooling in three different ways. One method 
is to cover water with oil from one inch to one inch and a quarter in 
depth. The second is to cool the pieces in a bath of a comparatively 
limited volume, so that the cooling is followed by a slight tempering, 
and the third is to withdraw the piece from the bath before it is com- 
pletely cooled. This last requires considerable skill, if uniform re- 
sults are to be obtained. 

Nickel Steel for Gears 

Nickel steel, when carbonized, is one of the best steels on the market 
for gears, as different tests have shown that 2 per cent of nickel added 
to the ordinary carbonizing steel will double, and in some cases more 
than double, the tensile strength after carbonizing, and these tests 
would prove that nickel steel should be used for carbonizing wherever 
the difference in price will warrant doing so. It is from 2 to 2i/^ 
cents per pound higher in price than the ordinary carbonizing steel, 
but the greater safety in manufacturing, and a consequent decrease in 
the number of spoiled pieces, will largely balance this difference in 
price. 

The different materials used in carbonizing have different effects as 
to the penetration of the carbon and the time required for a certain 



NICKEL STEEL 7 

penetration; but a general rule for the rate of penetration at different 
degrees of temperature is as follows, the time being eight hours: 

DEPTH OF PENETRATION OF CARBONIZING MATERIAL AT 
DIFFERENT TEMPERATURES 



Temperature. 


Depth of Pene- 


Temperature, 


Depth of Pene- 


Degrees P. 


tration, Inch 


Degrees F. 


tration, Inch 


1300 


0.000 


1750 


0.110 


1475 


0.0195 


1800 


0.125 


1565 


0.039 


1850 


0.165 


1650 


0.0625 


1900 


0.195 


1700 


0.080 


.... 





Thus it will be seen that a rise in temperature of 150 degrees doubles 
the rate of penetration, and in one case a rise of 90 degrees has 
doubled it. 

With the temperature held stationary at 1850 degrees the speed of 
penetration is as follows: 



Time, 


Depth of Pene- 


Time, 


Depth of Pene- 


Hours 


tration, Inch 


Hours 


tration, Inch 


% 


0.000 


4 


0.500 


y2 


0.020 


6 


0.800 


1 


0.310 


8 


1.200 


2 


0.400 




.... 



The steel used for carbonizing should not contain over 0.20 per 
cent of carbon, and the manganese component should be low, as this 
has a tendency to produce crystallization in annealing, and cause 
brittleness. 

The carbonizing material used should be of a definite composition 
which does not act abruptly, such as 60 per cent powdered charcoal 
and 40 per cent carbonate of barium. Two rules might be followed in 
treating: one is to carbonize at 1600 degrees F., cool to 1400 degrees, 
and quench; and the other is to carbonize at 1850 degrees, quench at 
1650 degrees, reheat, and quench a second time at 1400 degrees F. 

Nickel steel is not as high a grade of steel as nickel-chrome steel 
or the newer vanadium steel, but it stands a good second to these at 
about two-thirds the price, and is so much more easily machined and 
forged than nickel-chrome steel that it is often used in preference to 
the higher grades. 

Care Required in Forgringr and Working- 
In forging, great care must be taken to keep this steel at a high 
full forging heat and never hammer or roll it below this temperature, 
as cracks are then liable to appear. A great deal is said among the 
users of nickel steel about its cracking badly and being defective, and 
if defects occur in the bloom, they will almost always show up some- 
where in the finished product, but if the steel is properly rolled and 
forged these defects and cracks will not appear. Where carbon steel 
has been used for automobile axles and given way from fatigue, 
crystallization or other causes, heat-treated nickel steel has been sub- 
stituted, and has given perfect satisfaction. 



"8 No. 118— ALLOY STEELS 

Proportion of Carbon 
Frequently it is stated in advertisements and elsewhere that a 2 
per cent nickel steel is used for various parts of a machine, hut this 
means nothing by itself, as the properties of the steel depend as 
much upon the carbon content as on the nickel. To illustrate, one 
nickel steel that is largely used, and is the best for certain purposes, 
contains 2 per cent nickel and 0.12 per cent carbon. It has a high 



TABLE in. INFLUENCES OF DIFFERENT PERCENTAGES OF NICKEL IN 
NICKEL STEEL 



Per Cent 


Tensile 


Elastic 


Elonga- 




of 


Strength, 


Limit, 


tion in 


Treatment 


Nickel 


Pounds 


Pounds 


4.72 Ins , 






per Sq. In. 


per Sq. In. 


Per Ceut 




1 toli 


78,000 


48,000 


18 


Water tempered at 1650° F. 


2i to 3^ 


97,000 


82,500 


15 


Medium hard 


3Ho3^ 


80,000 


68,000 


20 


Medium soft 


2ito3^ 


85,000 


60,000 


23 to 13 


Medium hard, structural 


2i to 3^ 


71,000 


50,000 


28 to 16 


Medium soft, structural 


4ito6 


102,000 


74,000 


15 


Hard, for strenuous work 


4ito6 


121,000 


107,000 


12 


Hard, but annealed at 1600° F. 


4^ to 6 


88,000 


63,000 


20 


Medium hard 


16 to 18 


199,000 


114,000 


6 


Annealed at 1650° 


22 to 26 


110,000 


45,000 


40 


Annealed at 1650° 


22 to 26 


114,000 


50,000 


35 


Annealed at 1650° 


30 


80,000 


28,000 


44 


Annealed at 1650° 

Machinery 



tensile strength and very little elongation, while another nickel steel, 
equally good for other purposes, contains 2 per cent nickel and 0.9 
per cent carbon, and has a high tensile strength with a great 
elongation. 

Table III shows the different percentages of nickel in steel made 
by one firm, and the strength due to different treatments. These steels 
have a carbon content ranging from 0.10 to 1.00 per cent. Those with 
the highest percentages of nickel are used mostly for valves, owing 
to their heat-resisting powers, combined with a great strength. Some- 
times from 1 to 3 per cent of chromium is added to these valve metals 
to increase the elastic limit. 



CHAPTER II 



NICKEL-CHROMIUM STEEL 

Of the many higher grades of steel which have been brought out in 
the past few years, nickel-chromium steel has, by both laboratory and 
practical tests, been placed in the front rank as the highest grade of 
steel manufactured, and it is used on all classes of high-grade ma- 
chinery that require a steel of high tensile strength, high elastic limit, 
and a great resistance to shock and torsional stresses. It is one of 
the latest products of the steel maker. Ten or fifteen years ago this 
alloy of steel was comparatively little known, and it was a boast of 
the Germans "that the entire steel trust of the United States could 
not duplicate a Mercedes front axle." In the last few years that boast, 
however, has ceased to be true. To-day this alloy is being produced by 
a number of American steel makers at a price much below that which 
the Krupp works obtained for its highest grade of steel. Nickel- 
chromium steel is made in many different compositions, some of which 
are high in tensile strength, some in elastic limit, and others having 
different qualities, demanded by the different uses to which they are 
to be put. 

The Effect of Chromium 

Chromium added to steel in amounts up to 5 per cent increases the 
tensile strength and resistance to shocks, and diminishes the elonga- 
tion, while further additions lower the tensile strength. The elastic 
limit, in pieces not annealed, is raised at first, and afterward lowered. 
Chromium resembles carbon in its influence on the hardening quali- 
ties of steel. It refines the grain remarkably, owing to its tendency 
to prevent the development of a crystalline structure. Added to nickel 
steel, it overcomes the tendency of lamination and increases the elastic 
limit to figures that were impossible before it was brought into use. 
When nickel-chromium steel is given proper heat-treatment, it prac- 
tically shows no grain or fiber, thus possessing a high power of resist- 
ance to shock. This alloy also strongly resists the propagation of cracks 
which may be produced by sudden strains. Chromium intensifies the 
sensitiveness of the steel to the quenching process, and the resistance 
to fracture is higher than in carbon steel of the same degree of hard- 
ness; for this reason extreme hardness may be obtained.. Two per 
cent or more of chromium added to steel makes it very difficult to cut 
cold, although a special tool steel is made which overcomes this dif- 
ficulty to a large degree. The influence of chromium on steel becomes 
decisive above a content of one per cent. 

The effect of chromium on steel is best illustrated by the diagram. 
Fig. 1, adapted from Austen's "Introduction to Metallurgy." The lower 
dotted line shows the tensile strength of annealed pieces, the lower 



10 



No. 118— ALLOY STEELS 



full line shows the elastic limit of annealed pieces, the upper dotted 
line shows the tensile strength of the steel when hardened, and the 
upper full line shows the elastic limit of the steel when hardened. 

The reason why chromium steels do not fracture in heat-treatment 
as easily as carbon steels is due to the fact that in chromium steels 
the critical changes that take place when heating all steels to the 
hardening temperature take place more slowly. Chromium is also one 
of the best elements in a steel that is to be carbonized or casehardened, 
as it greatly increases the susceptibility of steel to heat-treatment and 
acts as a carrier of the carbon. Thus, in steels containing chromium, 
the carbon will penetrate to a much greater depth, and a higher per- 
centage will be absorbed by the outer layer in a given time, than with 
any other kind of steel, especially carbon steel. The increase in 



PERCENTAGE OF CARBON 

0.39 0.41 0.77 0.86 0.71 1.27 



'^-^'-*/4«0£ 




4 6 8 10 

PERCENTAGE OF CHROMrUM 



12 14 

Machinery 



Fig. 1. Diagram Showing Effect of Chromium on Steel 

depth of penetration of carbon is about 30 per cent of the penetration 
in ordinary carbon steels. 

The chromium refines the grain of the steel remarkably, owing to 
Its tendency to prevent the development of a crystalline structure. 
In the annealed state, every increase of chromium up to a content of 
6.50 per cent raises the tensile strength, while the elastic limit is 
gradually raised until a chromium content of 3.00 per cent is reached. 
This latter remains constant until the chromium content has passed 9 
per cent, but after this a rapid reduction takes place. In the hardened 
steels, both the tensile strength and the elastic limit increase until a 
chromium percentage of 5.00 per cent has been reached, and beyond 
this point both gradually decline. 

When 2.00 per cent of chromium has been added to a steel that has 
a carbon content between 0.75 and 1.50 per cent, it combines great 
hardness with ability to resist shock. It is one of the best materials 
for piercing armor plate, and is also used in making projectiles. A 
chromium content of 3.50 per cent in a tool steel that contains 8.25 
per cent of tungsten, gives the steel the well-known property of red 



NICKEL-CHROMIUM STEEL 



11 



hardness; that is, the hardness is not drawn and the cutting edge is 
maintained when using the tool at a red heat. A high percentage of 
chromium is also added to a steel that is forged between layers of 
wrought iron or soft steel and hardened in water. This is used in 
safes, vaults, etc., to make them burglar proof, and is also used for 
plough-shares and similar work. 

The presence of nickel in steel is very interesting in its influence, 
because, as mentioned in the previous chapter, when added in amounts 
up to 8 per cent, it increases the tensile strength, elastic limit, and 
elongation. Adding from 8 to 15 per cent of nickel produces a brittle- 
ness, and the mechanical properties are not ascertainable by experi- 
ment. With 20 per cent nickel a rapid rise in elongation is noticed, 
which increases very rapidly up to 25 per cent, after which the in- 
crease is more slow. Fig. 2 is a diagram fi'om Roberts-Austen's "Metal- 
lurgy," which illustrates these points. Nickel sometimes produces in 









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E«^ 


yo"" 


IN 4 


INC); 


ES_ 






-^ 


^=*^ 


--~. 






^ 


-I 





















^TIC 


LlWl 


r 














V. 


■\ 


2° 






/ 
































V 






































- 




) 10 20 30 40 50 60 70 80 90 1( 
PERCENTAGE OF NICKEL Machine 



ry 



Fig. 2. Diagram Showing Effect of Nickel on Steel 

steel a tendency to show laminations and to make it weak at right 
angles to the direction in which it is rolled. By the addition of 
chromium these laminations are removed, the metal is given a high 
degree of homogeneity, and the hardening can be performed more 
easily and without the danger of fissures appearing. 

In nickel steel, the tenacity and elastic limit is much increased by 
positive quenching up to about 5 per cent nickel, especially with high 
percentages of carbon. Below 0.50 per cent carbon and 5 per cent 
nickel the reduction of area remains nearly unchanged, and the elonga- 
tion but slightly decreases by heat-treatment, but when chromium is 
added these are both reduced nearly one half by heat-treatment. 



Effect of Silicon 

Silicon is sometimes used in nickel-chromium steel,, as it prevents the 
formation of blow holes and neutralizes the injurious tendencies of 
manganese. The majority of these steels, however, do not contain 
silicon, as its exact influence is not quite clear, and it is difficult to 
obtain silicon in steel without the presence of maganese. This makes 
its direct action difficult to determine. In quenching, silicon seems 
to influence steel the same as carbon in many ways, but this largely 
depends on the co-existing amount of the latter as well as of man- 



12 No. 118— ALLOY STEELS 

ganese. In general, only very small quantities are effective, and then 
only when the carbon content is low. Silicon will increase the tensile 
strength, but at the same time lower the elastic limit. 

Effect of Manganese 
Manganese is always a component of nickel-chromium steel, but over 
0.40 per cent is seldom allowed, as a steel high in manganese is dif- 
ficult to work cold, while otherwise nickel-chromium steel can be bent 
cold without difficulty. This has been proved by tests; in one case a 
connecting or piston-rod, after finishing, was bent double and showed 
no indications of cracks. Another rod was twisted two complete revo- 
lutions without injury. When the carbon is less than 0.50 per cent, 
and from 4 to 6 per cent of manganese is added, steel becomes so brittle 
that it can be powdered under a hand hammer, but by the addition 
of twice that amount of manganese the strength is restored. At 15 
per cent maganese, again, a decrease in toughness, but not in trans- 
verse strength, takes place. With 20 per cent and more of manganese 
a rapid decrease takes place. The discovery of these properties brought 
out manganese steel which has some remarkable qualities. The higher 
the percentage of carbon, the less manganese is necessary to bring 
about the result referred to. 

Influence of Phosphorus and Sulphur 
Phosphorus and sulphur are always components of steel, and prob- 
ably more time and energy has been spent to get rid of these, or re- 
duce them to a minimum, than on all other experiments. Phosphorus 
causes a "cold shortness" or brittleness in steel, and almost any quan- 
tity is injurious. No matter how high the tensile strength or elastic 
limit may be made by other components, if the phosphorus content 
is high, the metal will break when given shock tests. For this reason 
some object if phosphorus is present in amounts over 0.015 per cent, 
while others will allow as much as 0.04 per cent before they will agree 
that it is damaging to any serious extent. A high percentage of sul- 
phur, on the other hand, causes a "hot shortness" or brittleness be- 
yond a dull red heat, and is therefore not desirable when the metal 
is to be forged or worked hot. This component, however, is not as 
injurious as phosphorus. 

Composition of Nickel-chromium Steels 
The different combinations or percentages of the components of 
nickel-chromium steels are as varied as their makers, but the compo- 
sitions obtained have resulted in a very high grade of steel. Thus 
nickel is used in percentages of from 1 to 5; chromium from 0.5 to 
5; carbon from 0.25 to 0.45; silicon, when used, from 0.5 to 3; and 
manganese from 0.25 to 1. Table IV shows some of the nickel-chromium 
steels that are turned out by the different makers, both foreign and 
American, and their comparative strength. The first column shows 
one composition that is comparatively low in nickel and high in 
chromium, while the next three columns are low in chromium and 



NICKEL-CHROMIUM STEEL 



13 



high in nickel, other components being about equal. The last two 
columns contain the specifications that were adopted by the Associa- 
tion of Licensed Automobile Manufacturers. The only difference be- 
tween them is that one contains 0.45 per cent carbon and the other 
is 0.25 per cent. The physical characteristics of these two kinds are 
not derived from 'actual tests, but are the characteristics which they 



TABLE IV. DIFFERENT 


COMPOSITIONS 


OF NICKEL-CHROMIUM 


STEELS 


AND THEIR STRENGTHS 






Composition in Per Cent 


No. of 


















Sample 


Nickel 


Chromiun 


1 Carbon 


Silicon 


Mangan- 
ese 


Phos- 
phorus 


Sulphur 


1 


1.60 


4.41 


0.25 


0.20 


0.35 


0.012 


0.013 


2 


3.30 


1.40 


0.31 


0.20 


0.40 


0.012 


0.028 


3 


4.40 


1.50 


25 


0.24 


0.73 


0.013 


0.012 


4 


3.50 


1.50 


0.25 


25 


0.40 


018 


022 


5 


2.09 


0.71 


0.36 


0.21 


0.85 


0.025 


0.026 


6 


3.38 


1.87 


0.24 


.... 


0.35 


0.028 


0.030 


7 


1.50 


0.80 


0.25 




0.40 


0.030 


0.035 


8 


1.50 


0.80 


0.45 




0.40 


0.030 


0.035 




Fully Annealed 


After Heat-treatment 1 


.^"C 


•i^-s 


a 


"S 


.^--^ 


.tf t,J3 


c 




No. of 


o:SS« 


.SSS 


§Sa 


^.-^ 


..5SS 


.sss 


S?ic 


9 .fl 


Sample 




Hi 




■Bto 

T3 pL, 


III 


111 

1^^ 






1 


126,000 


115.000 


28 


64 


185,000 


160,000 


U 


48 


2 


115,000 


95,000 


24 


42 


155,000 


132,000 


38 


It) 


a 










154,000 


133,000 


12 


25 


4 


126,000 


115,000 


28 


64 










5 


112,000 


87,000 


14 


64 











6 


123,000 
85,000 


80,000 


10 


53 










7 


65,000 


20 


50 


130,000 


100,000 


12 


30 


8 


90,000 


65,000 


18 


35 


180,000 


140,000 


8 


20 



must possess when a test is made from a %-inch test bar, rolled from 
every heat and from two separate ingots. The actual tests may show 
much higher figures, as these are the lowest figures at which the steel 
will be accepted. The phosphorus and sulphur may, of course, be 
lower, as the percentage given is the highest that will be allowed. To 
the tests in this table there should be added a shock test, as all of the 
tests given might be satisfactory in their results, and yet, if too high 
in phosphorus, the metal would not stand shocks and torsional stresses. 
The steels in the table which are high in carbon are used principally 
for gears, and are the highest grades of steel in the market, either 
foreign or domestic, for this purpose. The nickel-chromium steels shown 



14 No. 118— ALLOY STEELS 

in the table that contain 0.25 per cent carbon are more extensively- 
used than those with higher carbon content, as they are forged more 
easily, and are machined and worked with less difficulty. These steels 
are used where great strength is demanded, combined with a light 
weight; hence, in automobile construction they are used for such parts 
as crankshafts, sprocket shafts, rear driving shafts, propeller shafts, 
axles, wheel pivots, and piston rods. Some racing cars have been built 
with all the working parts, as well as the frame, of nickel-chromium 
steel. These nickel-chromium steels are not as readily drop-forged as 
the ordinary carbon steel, and, therefore, the difference between con- 
secutive die forms should be less than in those used for ordinary steel. 
In forging, the metal should be heated to about 1380 degrees P., and 
kept at about that point until the operation is completed. Care must 
also be taken not to overheat or underwork the metal, as this pro- 
duces a coarse grain, which will show a low percentage of reduction 
of area, and the metal will be condemned on account of its inability 
to withstand the shock stresses. The best forging process is undoubt- 
edly the one using the hydraulic press, as with this the metal is 
slowly squeezed into the die, thus allowing the mass time to assume its 
new shape. The formation of crystals will not be able to take place, 
and the metal will be of a finer grain, with great density, producing 
less internal stresses and closing up any flaws which might have been 
in the center of the ingot. In hammer forging, unless the hammer is 
a large, slow-moving one, only the shell of the forged piece is af- 
fected, as the blows will not penetrate to the center. 

Heat Treatment 

Nickel-chromium steel is nearly always heat-treated, and great care 
should be used in doing this, as it is very easy to destroy the good 
qualities of the metal by inferior workmanship in this respect. The 
factors which influence the results of heat-treatment are: 

First: The physical and chemical components of the metal. 

Second: The gases and other substances which come in contact 
with the metal while heating. 

Third: The form of the temperature 'rise curve for each unit of 
the metal. 

Fourth: The highest temperature given to each unit of the metal. 

Fifth: The length of time at which the metal is kept at the 
maximum temperature. 

Sixth: The form of the temperature drop curve for each unit of 
metal. 

At about 570 degrees F. most steels lose their ductility and are not 
capable of resisting the strains of unevenly heated metal. Therefore, 
the temperature rise curve up to this point should be a gradual one; 
after this it may be as rapid as possible without overheating. Care 
must be taken not to overheat or burn the metal, as it is almost im- 
possible to bring it back to its former high standard. 



NICKEL-CHROMIUM STEEL 



15 



Nickel-chromium steel should be annealed after it has been worked 
and before heat-treatment, in order that it may return to its natural 
state of repose, as machining, forging, hammering, etc., is liable to 
throw it out of its homogeneity. It is annealed in a different man- 
ner from the ordinary grades of steel, it being heated to a tempera- 
ture of about 1470 degrees P., kept at this heat for four hours and 
then allowed to cool slowly in a slow-cooling furnace, or by packing in 
ashes or charcoal, the latter being preferred. If carbonizing is re- 
sorted to, this steel should be annealed, after carbonizing, as de- 
scribed above. 

To harden this steel, it should be heated to about 1470 degrees F. 
and made as hard as possible by quenching in oil or water, after 



TABLE V. 



CUTTING SPEEDS FOR DIFFERENT GRADES OF STEEL 
Depth of cut 1% inch and feed iV inch 



Kind of Steel 


Cutting 
Speed in 
Feet per 
Minute 


Pounds of 
Turnings 
per Hour 


Steel with 0.10 per cent of carbon 

Steel with 0.20 per cent of carbon 


100 

75 
63 
51 
55 

50 

m 

35 


295 
222 
176 
150 
163 

148 

135 

103 

Machinery 


Steel with 30 per cent of carbon 


Steel w^ith 0.40 per cent of carbon 


Steel with 3.50 per cent of nickel 


0.75 per cent nickel, 80 per cent chromium, 
and 0.25 per cent carbon 


1.50 per cent nickel, 0.80 per cent chromium, 
and 0.25 per cent carbon 


Steel with 1.5 per cent nickel, 80 per cent 
chromium, and 0.45 per cent carbon 



which it can be drawn to the different degrees required. Gears should 
be drawn by heating to 480 degrees F. to remove the internal strains. 
This makes the hardest and toughest gear which it is possible to pro- 
duce. It will stand an enormous amount of wear and shock stresses, 
and it is very difficult to break out a tooth with a sledge hammer. 

The carbonizing should be done by carefully packing the pieces to 
be carbonized in a cast-iron pot, in a mixture of powdered bone and 
charcoal. This should then be heated slowly until the temperature 
is raised to 660 degrees F., after which the temperature can be raised as 
fast as desired until 2100 degrees F. has been reached. The steel 
should be kept at this temperature for at least four hours, after which 
it should be allowed to cool slowly by taking the pot out of the fire 
and permitting it to cool without removing the cover. This anneal- 
ing, tempering, and carbonizing can only be done successfully and 
with positive assurance by the use of a furnace to which is attached 
a pyrometer, as the proper degrees of heat cannot be guessed at by the 
color of the metal. 



16 No. 118— ALLOY STEELS 

Machining- Nickel-chromium Steel 

Nickel-chromium steel is more difficult to machine than ordinary 
steel, and can only be done successfully when it is fully annealed and 
with high-speed tool steel. Under these conditions it should be cut at 
the rate of 35 feet per minute, the cut being 3/16 inch deep, with 1/16- 
inch feed. The comparison between the machining of this and other 
steels is best illustrated by Table V. 

This steel is only used where strength and lightness are more im- 
portant than cost. In automobile construction, it is only used on the 
higher priced cars and for the parts which have to stand the largest 
amount of strains and stresses. Its ability to stand these stresses bet- 
ter than the ordinary carbon steel was demonstrated by one motor car 
builder, by taking two round bars 1% inch in diameter, one of which 
was nickel-chromium steel and the other a mild carbon steel, fairly low 
in carbon, gripping both ends, leaving 9% inches exposed and sub- 
jecting them to a bending operation, the bending being 9/32 inch out 
of the true position of the center-line of the bars. This bending was 
made, back and forth, with the carbon steel bar 20,000 times before 
it fractured, while with the nickel-chromium steel bar 250,000 bendings 
were made before this fractured. Other tests which have been made 
show similar results. 

With the continued use of this grade of steel, its manufacture in 
larger quantities by the steel makers, and the improvements in ma- 
chinery and cutting steels, it will no doubt be cheapened both in the 
production and in its manufacture into finished products, so that its 
use can become more diversified, and better wearing qualities, lighter 
weight and greater strength given to the working parts of many 
classes of machinery. 



CHAPTER III 



VANADIUM STEEL 

Among the many new alloy steels which have been brought out in 
the last few years, the vanadium steels constitute one of the latest 
additions. These steels, in many different percentages of alloy, have 
been given numerous tests in order to determine the qualities of the 
steel and its action when submitted to the various strains and stresses 
it is liable to meet when put into actual use. These tests would seem 
to place it in the front rank of high-grade alloy steels, although it 
will be, after all, the actual use of this steel for the moving parts of 
machinery that will demonstrate to a certainty its wearing qualities, 
as well as its ability to withstand strains and stresses. 

The mechanical engineers of the present day have been forced to 
become better metallurgists than they ever were in the past, in order 
to intelligently design high-grade machinery, as the so-called "mysteri- 
ous" failures of steels are becoming more numerous and more pro- 
nounced every day. These failures of steel, which occur in high- 
grade alloys the same as in the Bessemer steel rails, although not as 
frequently, have proved to the engineers of to-day that the old custom 
of judging a steel by its resistance to static load and the amount it 
would stretch under that load is not always to be depended upon. The 
uses to which steel is put call upon it to resist strains applied in a 
totally different manner to that under which it was tested by simply 
pulling a bar until it broke. 

In machine construction, those parts which are liable to failure 
while in use require high dynamic qualities, that is, resistance to re- 
peated stresses, alternating stresses, simple repeated or alternating 
impacts, and fatigue, the latter being the outward and visible sign of 
the inter-molecular vibratory deterioration. Thus a new field is being 
opened out, and while vanadium affects steel in a manner that tends 
to increase the static strength, it also raises the dynamic properties 
to a very remarkable extent. Some recent tests of armor plate, made 
by the United States Government, give an illustration of this. In the 
past it has been the custom to make armor plate as hard as possible, 
and at the same time retain a high degree of strength. For this 
reason chromium was used as the principal alloy, and in many cases 
the only alloy, as it gave steel a hardness that was not obtainable in 
any other way. In the recent test spoken of, a vanadium-chrome steel 
was used with a hard outer shell and a very soft core, similar to the 
condition obtained by carbonizing. The result was that it withstood 
a much higher test of the impact blows delivered by the shots from 
a gun than the hard steels formerly used. 



18 No. 118— ALLOY STEELS 

"Vanadium and its Influence on Steel 

In an article in Machinery, May, 1911, Mr. William B. Snow gives 
a brief review of the main characteristics of vanadium and vanadium 
steel. Although vanadium has been used to a considerable extent for 
a number of years as an alloy for steel, one frequently hears the 
question asked: "What is vanadium, and how do vanadium steels 
differ from other steels?" Vanadium is an element, the existence of 
which was first recognized by a Mexican, Del Rio, about the year 1800. 
A number of years later it was discovered that the remarkable qualities 
of Swedish iron were due to the presence of a small amount of vanadium 
in the native ore. It is only quite recently, however, that vanadium 
has been found in sufficient quantities for commercial use. 

Pure vanadium is silvery white in appearance, and of very high 
melting point. In the pure state it has little or no practical applica- 
tion; for use as an alloy it comes in the form of ferro-vanadium, which 
usually contains from 30 to 40 per cent of vanadium. Vanadium is 
such a powerful alloy that it only needs to be used in exceedingly 
homeopathic doses to produce marked results. The use of as small 
an amount as 0.05 per cent of vanadium produces a strong scavenging 
action that indirectly toughens the steel to a most noticeable extent, 
by removing the oxide, nitrides, etc. The use of a larger amount — 0.18 
per cent, or more — causes a portion of the vanadium to combine with 
the ferrite or free carbonless iron in the steel, thereby directly tough- 
ening it. 

Vanadium is very volatile in its action, and considerable difficulty is 
experienced in getting it to mix thoroughly and evenly with the steel. 
When put into crucible steels it has a particularly aggravating tend- 
ency to go to the bottom of the pot in a lump, where it is frequently 
found after pouring. The higher the percentage of the vanadium, the 
greater the difficulty experienced in getting it to mix properly with 
the steel. It is practically impossible to put over 1.25 per cent of 
vanadium into steel and keep it there, while most vanadium steels 
do not contain more than 0.25 to 0.30 per cent of vanadium. 

In order to more fully understand its specific action, consider 
briefly what takes place when vanadium is put into steel. Steel con- 
sists of iron, with more or less carbon, sulphur, phosphorus, man- 
ganese, silicon, and, frequently, chromium and nickel. The carbon 
contained is combined chemically with a molecular portion of the 
iron. A molecule of this chemical compound alloys itself with 
twenty-one atoms of carbonless iron and the resultant alloy is dis- 
tributed in spots, or patches, through the carbonless iron. This alloy 
is known technically as pearlite, and the free carbonless iron as 
ferrite. Part of the manganese unites chemically with the sulphur in 
the steel, forming striae, or globules throughout the mass. The phos- 
phorus and the silicon, also the larger part of the nickel — if used — 
are dissolved in the ferrite in what is known as "solid solution." The 
chromium is found as a constituent of the pearlite. When vanadium in 
a sufficient amount is used, it goes into solid solution, partly in the 



VANADIUM STEEL 



19 



ferrite, which it toughens, and partly in the carbide portion of the 
pearlite, which it strengthens. 

Vanadium is also beneficial to steel in still another way, its use 
securing better results from the process of annealing, as will be seen 
from the following: When heat is applied to a bar of steel, as in 
annealing, it becomes sensibly hotter with each degree of heat ap- 
plied, up to a certain point, known as the point of decalescence. When 
the steel reaches this point, further application of heat does not in- 
crease the sensible temperature, but instead, a change takes place 
in the steel itself; the pearlite becomes broken up, its carbides going 




™ MMANESEi ^j Qg 7W15T3 IN E5''ELft5T!C Llf^T DF TDR51DN 43m INLB3. 




LDW CARBON, HIBH 



M/^MBANRSE TREA 



n :i% TWRT5 IN E4^e. EL A5TIC LIMIT DF TDR5IDN 3 7DQ IN.LBS. 




E, .r , ji 1 C LIMIT DF TDnSIQN 3 5DD INLB3. 



Fig-. 3. Axle Steel Samples showing Difference in Physical Qualities. Length, 

52 inches; Depth, 2 inches; Width, 11/2 inch; Thickness of Flanges, 

3/16 inch at Edge; 3/8 inch at Web; Thickness of Web, 3/16 inch 

into solid solution in the ferrite. When this change is completed, 
the sensible temperature of the steel again rises. In cooling, the 
reverse takes place; to a certain point, known as the point of re- 
calescence, the steel cools regularly, then it apparently ceases to cool, 
and a change takes place in the steel itself. The dissolved carbides 
are thrown out of solution, and alloy themselves with the ferrite to 
re-form pearlite. When this change is completed, sensible cooling 
again proceeds. 

Since the object of annealing is to break up the carbide areas and 
distribute them in small colonies, the steel is heated above the de- 
calescence point, the temperature being maintained long enough to 
thoroughly decompose the pearlite — as well as to remove any me- 
chanical strains that may have been locked up in the mass by previ- 



20 No. 118— ALLOY STEELS 

ous manipulation under hammer and rolls. It is then cooled slowly 
through the recalescence point, care being taken to prevent chilling. 
As a vanadium ferrite does not permit of the ready passage through 
it of the carbides re-precipitated at the recalescence point, the dis- 
tribution of the carbides in a vanadium steel is remarkably even. 
This greatly increases the toughness and tenacity of the steel, in 
addition to the greater toughness already obtained with the back- 
ground of vanadium ferrite (the portion of the vanadium that has 
gone into solid solution with the free carbonless iron). 

Properties of Vanadium Steel 
The peculiar properties of vanadium steel are best shown by the 
following comparative table of the physical properties of vanadium 
and other crucible steels: 

Tensile Elastic 

Strength, Limit, 

Pounds per Pounds per 

Condition of Steel — Natural, as rolled Square Incli Square Inch 

Carbon Steel 82,300 56,000 

Chrome-nickel Steel 102,100 69,230 

Chrome-nickel-vanadium Steel 118,100 87,500 

Chrome-vanadium Steel 153,220 98,560 

Condition of Steel — Annealed 

Carbon Steel 61,100 43,200 

Chrome-nickel Steel 81,200 56,700 

Chrome-nickel-vanadium Steel 96,350 69,300 

Chrome-vanadium Steel 112,000 76,160 

Condition of Steel — Oil tempered at 1500 deg., F., 
drawn to 600 deg. F. 

Carbon Steel 126,300 101,100 

Chrome-nickel Steel 150,300 134,500 

Chrome-nickel-vanadium Steel 163,700 152,300 

Chrome- vanadium Steel ■ 233,090 210,500 

From the above table it is seen that the two most marked char- 
acteristics of vanadium steel are its high tensile strength (breaking 
point), and its high elastic limit (stretching point). Another equally 
important characteristic is its great resistance to shocks; vanadium 
steel is essentially a non-fatigue metal, and therefore does not become 
crystallized and break under repeated shocks like other steels. Tests 
of the various spring steels show that when subjected to successive 
shocks for a considerable length of time, a crucible carbon steel spring 
was broken by 125,000 alternations of the testing machine, while a 
chrome-vanadium steel spring withstood 5,000,000 alternations, re- 
maining unbroken. 

Another characteristic of vanadium steel is its great ductility. High- 
ly tempered vanadium steel springs may be bent sharply, in the cold 
state, to an angle of 90 degrees or more, and even straightened again, 
cold, without sign of fracture; vanadium steel shafts and axles may 
be twisted right around several complete turns, in the cold state, with- 
out fracture. This property, combined with its great tensile strength. 



VANADIUM STEEL 21 

makes vanadium steel highly desirable for this class of work, as well 
as for gears which are subjected to heavy strains"^ or shocks upon 
the teeth. 

In the matter of heat-treatment, vanadium steels will stand a wider 
variation of temperature without detrimental effect than other steels. 
One particular characteristic of vanadium steel is the evenness with 
which is hardens. Vanadium steels forge readily, and, in the annealed 
state, are no harder to machine than an ordinary steel containing 
the same percentage of carbon. In this respect they differ greatly 
from other steels of high tensile strength, in which the presence of a 
considerable amount of nickel renders machining extremely difficult. 

The usefulness of vanadium as an alloy is not confined to steel 
alone; it is equally beneficial to other metals. Cast iron, brass and 
copper are much improved by the addition of a small percentage of 
vanadium, their strength and endurance being greatly increased. 
Castings from these metals show a finer grain and greater freedom 
from porousness through the use of vanadium. Aluminum, a par- 
ticularly difficult metal to machine, is greatly benefited in this respect 
by the addition of vanadium, which not only renders it easier to 
work, but also insures its ready flov/ in the mold, producing sharp, 
even castings from difficult shapes. 

The Practical Advantagres of Vanadium in Steel 

Vanadium, as mentioned, acts as a purifier on the metal, and very 
small percentages give the desired results; but if used in too large 
a percentage, it will spoil the metal. Sometimes the vanadium will 
perform this purifying action and leave but a trace to show on analyz- 
ing the steel, but in the majority of instances it stays in the metal. 
Vanadium steel, however, is the most difficult of all the alloy steels 
for the chemist to correctly analyze. 

Vanadium has the property of elusiveness to a very marked degree, 
and must be handled by the steel maker very carefully in order to get 
the necessary results. It is, therefore, marketed in the form of ferro- 
vanadium in the proportions of about two parts of iron to one part 
vanadium. For machinery purposes it is generally alloyed with steel 
in percentages of from 0.10 to 0.30 per cent, but it has been tried as a 
tool steel with as high as 3 per cent, and when this was compared 
with a 3 per cent tungsten tool steel by cutting a chilled white iron 
plate, and then collecting and weighing the cuttings, the vanadium 
tool steel was found to excel the tungsten tool steel by 25 per cent. 
It is used in manufacturing a tool steel by one steel maker, in this 
country, who uses vanadium in a small percentage, tungsten in a 
large percentage, chromium in a small percentage, and a few other 
ingredients in small percentages, and the results obtained from this 
steel show that it excels other tool steels by from 10 to 20 per cent 
in their cutting qualities. 

Vanadium is not like nickel, chromium, manganese and other 
mineral elements used in high-grade steel making, as it contains 



22 No. 118— ALLOY STEELS 

within itself no virtues, except in its action as a purifier on the other 
elements. Its most successful application lies in the direction of 
steels such as chrome-vanadium or nickel-vanadium. In a technical 
sense it retards the segregation of the carbides, thereby producing in 
steel a high degree of homogeneity and a grain of great uniformity 
and fine texture. In retarding the segregation of the carbides, vana- 
dium renders steel susceptible to great improvements by heat-treat- 
ment or tempering, and in this manner the steel can be prepared to 
resist wear and erosion. It also renders possible the natural forma- 
tion of the "sorbitic" structure which is necessary in metals which 
have to withstand wear and erosion. Vanadium steel also has self- 
lubricating properties to a greater extent than other high-grade steels, 
hence it is more valuable for shafts running in bearings and for 
gears. It also produces soundness mechanically as well as chemically 







TABLE VI. 








Tensile Strength 


Elastic Limit 


Elongation 


Reduction 


Specimen 


in pounds 


in pounds 


in 2 inches, 


of Area, 




per square inch 


per square inch 


per cent 


per cent 


A 


82,500 


50,000 


30 


66 


B 


116,000 


90,000 


21 


71 


C 


165,000 


147,000 


11 


61 


D 


165,000 


147,000 


16 


59 


E 


200,000 


185,000 


11 


56 


F 


228,375 




. . 


. , 


G 


198,750 


190,000 


9 


34 



and toughens the steel, thus conferring great powers of resistance to 
torsional rupture. 

Chromium gives to steel a brittle hardness which makes it very 
difficult to forge, machine or work, but vanadium, when added to 
chrome-steel, reduces this brittle hardness to such an extent that it 
can be machined as readily as a 0.40 per cent carbon steel, and it 
forges so much more easily that the Ford front axle — shown twisted 
in Fig. 3 — which is 52 inches long, 2 inches deep, of I-beam section, 
with the web only 3/16 inch thick, is being forged in three heats. The 
first heat is used to forge the straight I-beam part; the second heat 
is used to forge the arm for the steering-rod connection and the 
projections for the steering pivot on one end, while the third heat 
is required to forge the same on the other end of the axle. Auto- 
mobile axles of similar design, when formed out of chrome-nickel 
steel, require from 15 to 20 heats to give them the proper shape, and 
even then the dies give a great deal of trouble. For this reason the 
nickel or chrome-nickel axles are usually forged in two halves, and 
welded together in the center by the electric welding process. 

That vanadium steel can be machined as easily as ordinary carbon 
steel, that is, running at the same speed and using high-speed tools, 
is testified by the Ford Motor Co.: "We find in actual practice that 
vanadium steel costs no more than ordinary carbon steel and vastly 
less than nickel, because of the saving in machining, forging and 



VANADIUM STEEL 



23 



tempering, and the greater accuracy we are able to obtain, owing to 
uniformity of metal and the lighter weight of metal we are capable 
of using, owing to its great strength." 

Fig. 3 shows the comparative amounts of torsion which vanadium 
and some other steels will stand by twisting. Table VI. gives results 
of tests on various kinds of steel. A is a 0.06 per cent carbon steel, 
heat-treatied. JS is a 0.07 per cent nickel steel, heat-treated. The 
others are all taken from the same bar of vanadium steel and sub- 







TABLE VII. 








Tensile Strength 


Elastic Limit 


Elongation 


Reduction 


Specimen 


in pounds 


in pounds 


in 2 inches, 


of Area, 




per square incli 


per square inch 


per cent 


per cent 


1 


88,000 


64,500 


29 


59 


2 


98,750 


67,500 


25 


77 


3 


127,500 


110,000 


14 


59 


4 


147,000 


140,750 


17 


57 


5 


165,000 


155,000 


16 


55 


6 


176,500 


175,000 


7 


27 



jected to different degrees of heat-treatment. F merely shows the 
ultimate strength obtainable. 

Vanadium steel can also be given a wide range of strengths to- 
gether with hardness or softness by properly heat-treating. This is 
best shown by the accompanying Table VII. of test bars which were 
pulled on an Olsen testing machine by the Ford Motor Co. The 
test bars were all made out of one bar of steel. Specimens 1 and 2 
are in their softest condition; specimen 3 is in the condition of an 
axle; specimens 4 and 5 are in the crankshaft condition; and speci- 



TABLE VIII. 

Pendulum 
Kind of steel ^^P^^-*' 

pounds 

Carbon axle stock 12.3 

Nickel axle stock 14.0 

Vanadium axle stock 16.5 

Vanadium crankshaft stock 12.0 

Vanadium mesh gear stock.... 6.0 



Falling 
Alternating Weight on 



Impact, 

Number of 

Stresses 

960 

800 
2700 
1850 

800 



Notched 

Bar, 

Number of 

Blows 

25 
35 
69 

76 



Rotary 
Vibrations, 
Number of 

Revolu- 
tions 

6,200 
10,000 
67,500 



men 6 is in a mesh gear condition. Other tests have shown much, 
higher strengths, but the remarkable features of these tests are the 
way the elastic limit has been brought up nearly to the tensile 
strength, and the high reduction of area. 

While the static strengths before stated are and can be made the 
equal of almost any alloy steel, it is in the dynamic properties that 
vanadium steel excels all others, and these are becoming more and 
more the real tests of steel for use in moving machinery or where 
strains other than a direct pull are put upon it. These properties of 
vanadium steel as compared with carbon and nickel steel are shown 
by the tests given in the accompanying Table VIII. 



CHAPTER IV 



MANGANESE STEEL 

The following information on the subject of manganese steel is, 
mainly, abstracted from a paper by Mr, F. E. Johnson, read before the 
Association of Engineering Societies, October 21, 1910. 

Manganese steel was first successfully produced by the Hadfields 
in England about thirty years ago, and was known as "Hadfield steel." 
It was first made in the United States by the Taylor Iron & Steel 
Co., of High Bridge, N. J. About 1905 other foundries in this country 
took up its production, but they soon discovered that it was a very 
difficult metal to produce successfully, and comparatively few foundries 
are today engaged in manganese-steel making. In fact, the manufac- 
ture in the United States is almost entirely confined to two companies, 
the one mentioned above, and the Edgar Allen American Manganese 
Steel Co. The latter firm has two foundries, one at Chicago Heights, 
111., and one at Newcastle, Del. 

We might define manganese steel as a metal of the following com- 
position: 

Per Cent 

Manganese 11.00 to 15.00 

Carbon 1.00 to 1.20 

Silicon 0.25 to 0.40 

Phosphorus 0.06 to 0.11 

Sulphur 0.02 to 0.06 

Balance, iron. 

Variations from the composition given above have been tried, and 
steel has been made containing anywhere from 8 to 35 per cent of 
manganese, but commercial manganese steel contains at present about 
10 to 15 per cent of manganese and 1 per cent of carbon, these two con- 
stituents being the chief factors in manganese-steel making. Great 
care must be exercised in the manufacture so that the percentages of 
these two constituents are in the right proportion. Too much carbon 
and not enough manganese makes the steel brittle. 

Manganese steel is considered a very hard metal, because of the fact 
that it cannot be machined as readily as ordinary iron or steel. In 
fact, it is practically impossible to machine it with even the highest 
quality of tool steel. Tests made on the scleroscope indicate a hard- 
ness of about 30 for Bessemer steel, from 40 to 50 for manganese steel, 
and from 65 to 70 for chilled cast iron; yet it has been demonstrated 
again and again that manganese steel will outwear chilled cast iron 
many times over. In general, it is safe to say that it will wear from 
four to eight times as long, depending upon the purpose it is used 
for and the conditions under which it works. The secret of the resist- 



MANGANESE STEEL 25 

ance of manganese steel to abrasive action seems to be due to its 
ability to "flow" or endure repeated distortion. Under abrasive action 
it simply moves away from one place to another, but does not actually 
wear off. One can take, for example, a square corner of a piece of 
manganese steel and peen it over, and then pound it back to a square 
corner, and keep up this operation without actually being able to 
remove any material. 

Manganese steel is very sensitive to heat. A statement given out by 
the Edgar Allen American Manganese Steel Co. contains some interest- 
ing information on this point. Manganese-steel castings should never 
be heated, because if heated to a temperature of only 400 degrees F., 
they will lose their toughness and strength to a remarkable degree. 
This applies to castings of plain design; castings of irregular design do 
not even stand as high a heat as 400 degrees F. A casting which is 
in perfect condition and free from internal stresses at the time it 
leaves the foundry is very likely to break or crack if heated. The 
company strongly disclaims any responsibility for the breakage of any 
manganese-steel castings which have been heated after their ship- 
ment from the company's foundry. 

Manganese steel will not become a permanent magnet; hence it is 
used for disks in magnetic hoists, as the smallest particle of iron or 
steel will not cling to it after the current is shut off. The tensile 
strength of early specimens, determined by Hadfield in England, was 
150,000 pounds per square inch, with an elongation as high as 50 per 
cent. The average commercial steel of today, however, has a tensile 
strength of 82,000 pounds per square inch, an elastic limit of 45,000 
pounds and an elongation of 30 per cent. Forged manganese steel 
will give better results, but there is very little commercial forged 
manganese steel made at this time. 

Manufacture of Mang-anese Steel 

The manufacture of manganese steel is carried on with a great de- 
gree of secrecy, and for this reason full information on some of the 
processes employed cannot be given. The steel is composed chiefly of 
a mixture of scrap iron and pig, this mixture being very carefully 
made up according to the predetermined composition of the steel. 
The mixture is melted in an ordinary cupola such as is used in any 
foundry, and is then run into a converter and blown quite similarly to 
Bessemer steel. This process, however, is carried out with great care 
and is directed by one man only, who operates everything from the 
central station or platform close to the converters. After the steel is 
blown, it is poured into large ladles from which the slag is removed. 
The manganese, which has previously been melted in graphite crucibles 
under intense heat, is then added. From the large ladles it is poured 
into sand molds which are practically the same as ordinary molds for 
cast iron. 

One difficulty with manganese-steel castings is the excessive shrink- 
age when cooling. Manganese steel shrinks 5/16 inch per foot, which 



26 No. 118— ALLOY STEELS 

is nearly three times as much as the shrinkage of ordinary cast iron. 
All ladles and molds are kept very hot so as not to chill the metal 
before it is poured, as in this case a homogeneous casting could not be 
produced. After the casting process is completed, the castings are 
all subjected to a heat-treatment, or both heat-treatment and water 
submergence. This part of the process is kept secret by the manu- 
facturers. 

Manganese-steel castings can only be successfully made to certain 
sizes as regards length and particularly as regards cross-sectional area, 
the thickness being the prime factor. The greatest thickness of any 
section that has been successfully cast, up to date, is about 4l^ inches. 
It is also very difficult to cast small or thin sections, the lower limit 
being about % inch for ordinary castings. The reason that the thick- 
ness is so important is because of the after treatment, which apparently 
will only penetrate to a certain depth. Thin sections are limited by 
the flow of the metal. 

Owing to the fact that manganese steel cannot be cut by ordinary 
cutting tools, all machining on manganese-steel castings must be done 
by means of grinding. Sometimes steel bushings and other pieces 
of ordinary soft steel are inserted in the molds and cast into the 
casting, making it possible to bore out, drill or tap the casting at cer- 
tain places. For example, the hubs for car wheels may be provided 
with soft steel bushings, and soft steel inserts may be provided for 
set-screws, etc. 

Uses for Manganese Steel 

The uses of manganese steel are not very extensive at present, due 
partly to its high first cost, and partly to the difficulty of machining 
the steel. It is used mostly for castings subjected to heavy strains 
and shocks and excessive wear, such as the wearing parts of steam 
shovels, ore and rock crushers, mining machinery, etc. It is also used 
to a considerable extent for safes. When rolled and forged, it is 
used for rails, frogs and crossings. The use of manganese steel has 
made it possible to cut down the maintenance cost for many machines 
very materially. 

It may be of interest to emphasize the fact that manganese steel 
has proved itself efficient when used in cases where it is subjected to 
shocks. An idea prevails among railway engineers that this steel will 
not stand shocks. As an experiment, therefore, a manganese-steel frog 
weighing 800 pounds was bent under a drop weight. The frog was 
subjected to 165 blows from a weight ranging from 1250 to 2500 pounds 
and falling from a height varying from 3 to 23 feet, the total energy 
exerted being nearly 1,700,000 foot-pounds. No fracture or impair- 
ment of any nature could be discovered. There are hundreds of 
manganese-steel frogs and cross-overs now in use. At the North- 
western Terminal, in Chicago alone, there are 200 frogs of this kind 
installed. 



CHAPTER V 



TITANIUM STEEL 

Titanium is one of the elements that have been successfully used to 
improve the quality of steels. It has also been very successfully used 
for cast iron and for some of the non-ferrous metals. The first heat 
of titanium steel made in America was poured in 1907, and since that 
time a great deal of investigation has been conducted and many ex- 
periments have been made. These tests have shown that when ferro- 
titanium has been added to steel or iron in very small quantities, it 
has greatly strengthened these metals and improved their qualities in 
other ways; it can now be considered one of the best of purifying ele- 
ments that have been used in the manufacture of steel. 

Titanium belongs to the same chemical group as silicon, and three 
other elements that are quite rare. It forms a compound with oxygen, 
called titanium dioxide (TiOa), occurring in nature in three distinct 
forms, the principal one being the titaniferous iron ore so often en- 
countered. In some respects it resembles carbon. Like many of the 
other elements, it is very difficult to control and make use of when 
a natural ingredient of the iron ores; it is therefore necessary to 
separate it in the electric furnace and manufacture it into ferro- 
titanium containing from 12 to 15 per cent titanium, about 6 per cent 
of carbon and 5 per cent of all other impurities, with the balance iron. 
This, when correctly added to steel or iron, can be made very bene- 
ficial. With this percentage of titanium, it enters into almost instant 
solution; but as titanium has a much higher melting point than iron, 
a higher percentage would cause the titanium to segregate and no 
beneficial results would be obtained. 

"While nickel, chromium, molybdenum and tungsten add certain good 
qualities to steel, none of these combines with nitrogen, thus remov- 
ing it from the metal, in the way titanium does. Its combination with 
nitrogen gas takes place with the evolution of heat, and it is the only 
undisputed example of the combustion of an element in nitrogen. 
When heated in oxygen it creates an instantaneous dazzling flame. 

That oxygen and nitrogen are very injurious to steel and decrease 
its strength, wearing qualities, etc., is now a recognized fact; that 
these elements are present in larger quantities than has been previ- 
ously supposed is also recognized. When titanium is added to the 
molten metal, it combines with these gases, which otherwise are 
liable to become occluded in the steel, and carries them off into the 
slag. These gases also form miniature bubbles that, when segre- 
gated, form holes large enough to be plainly seen. If segregated in 
large enough masses they form good-sized blow-holes. 

Oxide forms when oxygen comes in contact with iron, and is present 
in very small black specks throughout the steel. This oxide can only 



28 No. 118— ALLOY STEELS 

be seen when the surface has been perfectly polished and magnified 
at least 1000 times. It is invariably found in steels that produce 
blisters when pickling, and this leads to the conclusion that the 
blisters are formed by the reduction of oxide by the hydrogen evolved 
during the pickling process. High-carbon steel rods that contain the 
same impurities occasionally fracture in the pickling bath, and doubt- 
less the same pressure that blows a blister in mild steel will cause a 
rupture in hard steel. 

Owing to the gaseous nature of both oxygen and nitrogen, it has 
been difficult to analyze steels for these contents. Some recent in- 
vestigations, however, showed that the percentage of oxygen in some 
twenty-four samples of steel ranged from 0.021 to 0.046 per cent. 
These percentages may seem to be so extremely small that they could 
be ignored. But the amount of an element present, however, should 
not alone be considered, when judging its influence on steel; the com- 
binations that the element forms should be taken into consideration. 
When mention is made of 0.05 per cent of sulphur, it is in reality the 
0.13 per cent of manganese sulphide that affects the quality of the 
metal. Oxygen has only half the atomic weight of sulphur and is 
capable of forming larger quantities of compounds; therefore, it ex- 
erts a greater influence. Thus where 0.05 per cent of sulphur cor- 
responds to 0.13 per cent of manganese sulphide, 0.05 per cent of 
oxygen corresponds to 0.22 per cent of ferrous oxide. This percentage 
is therefore high enough to very materially affect the qualities of 
steel. 

Influence of Nitrogen on Steel 

It has been shown by some recent investigations that, at first, an 
increase of nitrogen causes the toughness of steel to slightly increase, 
but reduces its ductility; each increase of nitrogen causes the elonga- 
tion to rapidly diminish. Steel with 0.5 per cent carbon loses its 
ductility in the presence of 0.040 to 0.047 per cent of nitrogen. In 
a one per cent carbon steel, the elongation and contraction become nil 
when the nitrogen content reaches 0.030 to 0.035 per cent. In the 
softer steels, this happens when the nitrogen content reaches 0.050 to 
0.065 per cent, and in the very soft steels, with about 0.08 per cent 
of nitrogen. 

Open-hearth steel usually contains from 0.020 to 0.025 per cent of 
nitrogen; Bessemer steel from 0.018 to 0.062 per cent; and crucible 
steel runs from 0.010 to 0.015 per cent in nitrogen. Thus, a nitrogen 
content of at least 0.012 per cent must nearly always be reckoned 
with. Steels made in the resistance electric furnace are an exception 
to this, as they are practically free from nitrogen. Steels, however, 
that are made in the arc electric furnaces, in the presence of basic 
slags, are liable to contain injurious amounts of nitrogen. 

Titanium has a very strong affinity for both oxygen and nitrogen; 
it forms with oxygen an oxide, and with nitrogen, a stable nitride 
that shows as tiny red crystals under the microscope. Both of these 
are then carried off into the slag and the quantity of slag that is lifted 



TITANIUM STEEL 29 

from the molten metal is quite materially increased. The deoxidation 
of steel is usually accomplished with manganese and silicon, but 
these never remove the oxides as thoroughly as is desired. Titanium 
is a much more powerful deoxidizer than either or both of these; 
when added to steel at the time of tapping, it completes their un- 
finished work and reduces the oxygen and nitrogen to mere traces. 
If a greater amount of titanium is used than is needed to remove the 
oxides and nitrides, it will afterward attack the sulphur and phos- 
phorus and if it does not remove them, it counteracts their injurious 
effects upon the steel. The phosphorus may be made to pass into the 
slag as phosphate of titanium by using special means. The reaction 
of titanium on the sulphur has a tendency to carry it off in the form 
of a sulphide or sulpho-cyanide of titanium. Cupro-ammonium etching 
tests show the low sulphur and phosphorus content of titanium-treated 
steel. The very energetic reaction of the titanium and nitrogen takes 
place at a temperature of about 1475 degrees F. The good effects of 
their union can easily be lessened by a careless shutting off of air, thus 
permitting the formation of titanium and nitrogen combinations that 
are of no value. 

How easily nitrogen finds its way into steel is shown by a heat of 
Bessemer steel that had been over-blown three minutes. This was 
found to contain 0.032 per cent af nitrogen, whereas the normal steel 
contained only from 0.012 to 0.022 per cent. Another heat of Bessemer 
steel containing from 0.013 to 0.014 per cent of nitrogen was treated 
with one per cent of titanium and this reduced the nitrogen to from 
0.004 to 0.005 per cent. 

Method of Adding- Titaniura 

When possible, it is always best to add the ferro-titanium to the steel 
while it is being tapped into the ladle, and after the ferro-manganese 
has been added. It is lighter than iron and would not sink and dis- 
seminate if it were added near the top; hence, it should be shoveled 
in gradually while the steel is flowing into the ladle. Titanium-treated 
steels should be held in the ladle for from 5 to 15 minutes before pour- 
ing, in order to allow the titanium to do its work and scavenge out 
the oxygen and nitrogen. It is difficult to influence steel makers to 
hold the steel that long in the ladle, as without the titanium it would 
become chilled in a much shorter time. Titanium, however, raises the 
temperature and the metal is in better condition for pouring after 
standing than before. Owing to an accident, one ladle had to be held 
20 minutes after tapping and adding the titanium and it was then 
found to be in better condition for teeming into ingots than the 
ordinary steel that is teemed as soon as the ladle is filled. This is a 
statement that is very difficult to make steel makers believe; but 
the evidence is very conclusive and can easily be obtained. 

When commencing the use of titanium, one per cent should be 
added to the bath; this can gradually be reduced until the beneficial 
results obtained reach the high point and begin to diminish. In most 



30 



No. 118— ALLOY STEELS 



cases one-lialf of one per cent is all that can be made to bene^t the 
metal. In manufacturing Bessemer steel rails, this latter percentage 
only increases their cost about $1.50 per ton. It is antagonistic to 
aluminum and. the two should never be used together, for aluminum 
adds brittleness to steel, while titanium removes brittleness. 

By removing the oxygen and nitrogen, titanium prevents the forma- 
tion of blow-holes in steel. This is well illustrated by the two pieces 
shown in Fig. 4. The one containing blow-holes was cast without any 
titanium, while the piece without blow-holes was cast from the same 
metal after 0.5 per cent of titanium had been added. The reaction of 
the titanium raises the temperature of the bath and makes it more 
liquid by freeing it from the free oxide and slag. This allows the 
m.etal to subside in the mold while cooling and the pipe is smaller 




Fig, 4. Blow-holes removed from Cast Iron by Titanium 



and flatter. The metal invariably lies dead in the ingot molds and does 
not boil. By removing the occluded gases and slag from steel, titanium 
increases the density of the metal and retards any tendency towards 
segregation, thus making a much more homogeneous metal. It also 
increases the tensile strength, elastic limit, contraction, transverse 
strength and ductility of steel. It greatly improves its resistance to 
frictional or abrasive wear, and resistance to shock, torsional and im- 
pact strains. 

Tests of Titanium Steel 

One example of the ability of titanium steel to withstand torsional 
strains was obtained by twisting through seven complete revolutions; 
a bar four feet long and one and one-eighth inch square; there was no 
sign of a fracture. The Brinell hardness test shows a titanium-treated 
steel to be softer than one not treated with titanium. 

One recent test of some structural steel showed that before it was 
treated with titanium, it had a tensile strength of 67,000 pounds per 
square inch and an elastic limit of 42,000 pounds, the elongation being 



TITANIUM STEEL 



31 



24 per cent, and the contraction, 40 per cent. After this same metal 
had been treated with 0.50 per cent of titanium, the tensile strength 
was 77,120 pounds per square inch, the elastic limit, 51,750 pounds, the 
elongation, 25 per cent, and the contraction, 43 per cent. 

Another heat of steel that was rolled into billets and then into iron 
rods of slightly less than 14 inch diameter, had a tensile strength of 
114,400 pounds per square inch, an elastic limit of 91,000 pounds per 
square inch, an elongation of 28 per cent, and a contraction of 52 
per cent; ordinarily, 90,000 to 95,000 pounds per square inch is the 
tensile strength of this metal. This 20 per cent increase in tensile 
strength was doubtless due to the titanium removing the occluded 
gases and slag. 

The resistance of titanium steel to abrasive or frictional wear is well 
shown by comparing the steel rails illustrated by Figs. 5 and 6. In 




DOTTED LINES SHOW 
ORIGINAL SHAPE OF 
.RAILS 




Machinery, N. Y. 



Fig. 5, Ordinary Bessemer Rail 
Showing- Wear in Nine Months 



Fig. 6. Titanium-treated Bessemer 

Rail Exposed to Same Amount 

of Wear 



Fig. 5 is shown an ordinary Bessemer rail that was laid October 7, 
1909, and measured July 8, 1910, to get the shape as shown and thus 
show the amount of wear. Fig. 6 shows the shape of a titanium treated 
Bessemer rail that was laid next to that shown in Fig. 5 on the same 
date and measured on the same date. The ordinary Bessemer rail 
lost 7.03 pounds per yard during the 9-month wear, while the titanium 
treated rail only lost 1.39 pound per yard. Another method of test- 
ing for abrasive wear is performed with the machine shown in Fig. 
7. This shows a section of a steel rail placed upon the top of a re- 
volving plate, coated with abrasives, and held down by a lever. On 
the handle of this lever a block of iron of known weight is hung, as 
shown. 

Titanium treated steels have recently been extensively tried for 
gears, plates, rolls, tires, castings, etc., and have almost invariably 
shown a reduction of brittleness and an increase of durability. One 
method of testing this is by the machine shown in Fig. 8. In this, bar 
A is held in the machine and bent around a 1-, 2- or 3-inch center, as the 
case may be, located at B. Different sized centers are shown at C, 
D and E. 



32 



No. 118— ALLOY STEELS 





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TITANIUM STEEL 



33 



and the sulphur and phosphorus slightly increased, the effect of the 
titanium remaining practically the same as before. 

The endurance of titanium treated steel has been well demonstrated 
by tests that were given it on the White-Souther rotary vibrational 
testing machine shown in Fig. 9. An open-hearth steel that con- 
tained 0.25 per cent carbon, 0.64 per cent manganese, 0.425 per cent 
silicon, 0.04 per cent phosphorus, and 0.035 per cent sulphur, with- 
stood 2,660,000 revolutions at a fiber stress of 38,870 pounds. After 
this same steel had been treated with titanium, it was given 4,052,200 
revolutions at the same fiber stress, namely, 38,870 pounds. The stress 
was then increased to 40,600 pounds and the piece stood 10,800,700 



TABLE IX. DROP TESTS OF RAILS 



Number of Drop 


1 


2 


3 


4 


^ 


Deflection in Inches 


Condition 


1.3 
1.4 

1.4 
1.5 
1.5 
1.5 
1.4 
1.4 
1.4 
1.5 
1.6 
1.6 
1.6 


2.5 
2.5 
2.6 

2.7 
2.1 
2.1 
2.7 
2.7 
2.2 
2.7 
2.9 
3.1 
3.1 


3.5 

3.6 
8.9 
4.0 
4.1 
4.1 
3.1 
4.1 
3.4 
3.9 
4.1 
4.4 
4.2 


Straight 
straight 
Straight 
Bent other way 
Straight 
Broke 
Straight 
Straight 
Straight 
Straight 
Straight 

Bent 

Bent 


Broke 
Broke 
Broke 
As before 
Broke 


Quite straight 

Broke 

Broke 
Quite straight 
Flange broke 
Flange broke 
Flange broke 

Machinery 



additional revolutions without a fracture. The fiber stress was again 
increased to 42,400 pounds and the piece given 1,918,600 more revolu- 
tions. The stress was increased a third time to 44,200 pounds and 
the piece was given an additional 1,006,300 revolutions before it broke. 
This was a total of 18,274,900 revolutions for the titanium steel, many 
of which were given it at an increase of fiber stress, as against 2,660,000 
revolutions for the untreated steel. 

For these tests a bar is placed in the machine as shown at F, and 
revolved by the belt and pulley while the weights located at G and H 
produce the fiber stress. As it is well known that iron is ductile in 
proportion to its purity, this increase in rotary vibrational strains can 
only be attributed to the purifying properties of the titanium which 
by removing the oxygen, nitrogen, etc., increases the cohesive force 
between the molecules and makes the steel more homogeneous. In 
increasing the ductility it does not soften the metal enough to weaken 
it, but on the contrary increases its strength. By removing the oc- 



34 



No. 118— ALLOY STEELS 



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TITANIUM STEEL 



35 



machines have a cyclometer attached to register the number of revo- 
lutions or alternations given the sample. 

Impact tests of the steel are made in the machine shown in Fig. 11. 
In this, only the lower part of the machine could be shown, as it 
passes through the ceiling. The upper part is only a guide for the 
weight and, in this machine, extends 20 feet above the platen. The 
test piece is placed on platen E, and weight L is dropped on it, from 
a given height. When weight L strikes the test piece, the springs 
under platen K cause pointer N to register the foot-pounds of the 
blow, on dial M. 

Some tests on titanium treated steel rails that were 85 pounds to 
the yard were conducted in a similar way. Rails were cut up into 
3-foot 6-iiich lengths, laid on supports three feet apart, and a weight 

TABLE X. TURNING TESTS WITH TOOL STEEL 



Number 


Titanium 


Depth of 


Width of 


Speed in 


Minutes 


Condition 


of 


Content. 


Cut 


Chip 


Feet per 


Tool was 


of Tool 


Tool 


Per Cent 


in Inches 


in Inches 


Minute 


Used 


at End 


1 


None 


h 




27 


70.0 


Blunt 


2 


Noue 


.V 




27 


71.5 


Blunt 


3 


0.25 


eV 




27 


109.2 


Blunt 


4 


0.35 


-h 




27 


117.2 


Blunt 


5 


None 


ix 




32 


28.2 


Blunt 


6 


None 


-bh 




32 


42.8 


Blunt 


7 


0.25 


ix 




32 


63.3 


Blunt 


8 


35 


if 




32 


76.4 


Blunt 


9 


Nooe 


ii 


A 


50 


25.4 


Blunt 


10 


None 


-h 


z\ 


50 


70.6 


Blunt 


11 


25 


-h 


,% 


50 


97.2 


Blunt 


12 


35 


A 


h 


50 


133.2 


Blunt 

Machinery 



of 2000 pounds dropped on them from a height of 17 feet. Three blows 
were given on the head and the deflection measured. Then the rail was 
turned over and the fourth and fifth blows were given on the base. 
Table IX gives the results of these tests. 

Titanium in Tool Steels 
Titanium-treated steel can be made by the crucible process and 
only increases the cost of the metal $2.50 per ton when one per cent 
of titanium is used. Some experiments and tests were conducted on 
titanium steels in Sheffield, England. In these steels enough titanium 
was used to give 0.25 per cent and 0.35 per cent of the titanium in 
the finished steel. An ordinary tool steel with a tensile strength of 
127,000 pounds per square inch was used. Six lathe tools were made 
from it before the titanium was used. The metal was then treated with 
titanium and six more tools made. One tool with titanium and one 
without turned the same bar at the same time. Thus tools 1 and 3, 
5 and 7, and 9 and 11 were used together and tools 2 and 4, 6 and 8, 
and 10 and 12 were used likewise. The tools were all given the same 
heat-treatment and the results that were obtained are shown in 
Table X. 



36 



No. 118— ALLOY STEELS 



In some experiments that were made by tool-steel makers in the 
Pittsburg district, it was found that if 0.50 per cent of titanium was 
retained in the steel, it would give cutting tools much greater dur- 
ability and high-speed qualities. A special method is required, how- 
ever, to retain any of the titanium in the steel, as its great affinity for 
oxygen and nitrogen causes it to go off into the slag. By removing the 
impurities, the titanium causes the metal to heat more slowly in the 
forge and also to retain the heat longer after it has been worked 
and become cold. This property of heating more slowly causes the 
cutting edge to last longer, as the temper is retained longer. The re- 
sistance to corrosion will also keep the tools from rusting, to a cer- 
tain degree, when laid away. 

As steel treated with titanium shows greater resistance to abrasive 
and frictional wear, it heats up more slowly from friction. Thus 



TABLE XI. TESTS OF GRAY IRON CASTINGS WITH AND WITHOUT TITANIUM 



Without Titanium 


With 0.5 Per Cent of Titanium 


Sample 


Crushing 
Strength 
in Pounds 


Deflection 

in 

Inches 


Sample 


Crushing 
Strength 
in Pounds 


Deflection 

in 

Inches 


1 

2 
'S 
4 
5 
6 


2,240 
2,260 
2,010 
1,840 
1,970 
2,150 


0.10 
0.10 
0.09 
0.08 
0.08 
0.10 


! 1 

i 2 
3 
4 
5 

6 

1 


3,050 
8,140 
3,150 
3,230 

2,850 
2,990 


0.09 
0.10 

0.10 
0.10 
0.10 
0.09 


Average 


2,078 


0.09 


Average 


3,068 


0.10 

Machinery 



whether it be the tool or the work that is treated with titanium, the 
machine work can be performed more quickly, as the cutting speed 
can be increased; whether the tools be of the carbon or high-speed 
kind, makes no difference about increasing the speed. One instance of 
the slow heating of titanium treated metal was shown in some ingot 
molds that did not show red in the dark when filled with molten 
metal; whereas ordinary ingot molds filled at the same time and 
standing beside them, were distinctly red hot. 

Steel castings that have been treated with titanium are more blue 
in color, freer from blow-holes and brittleness and heat up more 
slowly from cutting tools than ordinary steel castings; they can thus 
be machined more easily and rapidly. The No. 3 Government specifi- 
cations for cast steel have been difficult to meet without resorting to 
several heat-treatments. They call for a tensile strength of 85,000 
pounds per square inch, an elastic limit of 45,000 pounds per square 
inch, an elongation after rupture of 12 per cent, and a contraction of 
18 per cent. By the use of 8 pounds of 10 to 15 per cent ferro-titanium 
to a ton of metal, the difficulties have been overcome by one foundry. 



TITANIUM STEEL 37 

In fifteen heats before the titanium was used, the average tensile 
strength of castings after the first annealing was 81,633: pounds per 
square inch, the elastic limit was 47,233 pounds per square inch, the 
elongation, 15.1 per cent, and the contraction, 18.9 per cent. The 
fifteen heats after this, that contained titanium, produced castings with 
an average tensile strength of 91,533 pounds per square inch, an elastic 
limit of 50,000 pounds per square inch, an elongation of 19.2 per cent, 
and a contraction of 24,3 per cent. The steel that entered into the 
castings was made in a Tropenas converter, and was free from blow- 
holes, homogeneous, and very uniform in its properties. 

Very exhaustive tests have been made of the effect of titanium in cast 
iron and Table XI shows the comparison between gray iron as cast 
without titanium and with 0.5 per cent of titanium added. These tests 
were made in the machine shown in Fig. 12. The test bar is laid on 
the supports and P while block R is forced down on it. The de- 
flection and number of pounds required to break the piece are then 
measured. The transverse strength has been increased from 17 to 
23 per cent by the use of titanium. It also increases the breaking 
stress, wearing qualities and hardness in the chill of cast iron; but 
it decreases the chilling effect. 



CHAPTER VI 



NATURAL ALLOY STEEL 

Natural alloy steel is rapidly becoming an important material in 
the manufacturing field. It derives its name from the fact that the 
steel is manufactured from an ore in which nickel and chromium are 
alloyed by nature. While such ores have been known to exist for 
some time, it is only within the last decade that ores were discovered 
that had a uniform composition and existed in quantities sufficiently 
large to warrant their manufacture into steel. 

Shortly after the Spanish-American War, such ore was discovered 
at Mayari and Moa in the Province of Oriente, in the eastern part of 
Cuba. These ores showed a remarkable uniformity of composition and 
covered some 25,000 acres on a plateau on the northern slope of a 
mountain range. In this place there is something like 1,000,000,000 
tons of ore in sight, low in phosphorus and sulphur. The Pennsyl- 
vania Steel Co., Steelton, Pa., obtained the control of these ore beds 
and is, besides the Maryland Steel Co., Sparrows Point, Md., the only 
company manufacturing steel billets, blooms, bars, and miscellane- 
ous forgings from the ore. The steel made by the Pennsylvania Steel 
Co. is known by the trade name "Mayari steel." Other companies pur- 
chase the billets, bars, etc., and roll and forge them into commercial 
shapes. The Philadelphia Steel & Forge Co., Philadelphia, Pa., is one 
of these firms; it has given the product the trade name "natural alloy 
steel," while the Carpenter Steel Co., Reading, Pa., calls it "Samson 
steel." Both of these latter firms make a specialty of rolling and 
forging shapes suitable for automobile parts, but they also manu- 
facture the steel into bars and shapes that can be used for die-blocks, 
spindles, tools, and for numerous other purposes. 

The various grades of steel into which this ore is manufactured 
contain from 1.00 to 1.50 per cent of nickel; from 0.20 to 0.70 per cent 
of chromium; from 0.30 to 1.50 per cent of carbon; and from 0.50 to 
0.80 per cent of manganese; the silicon is kept below 0.20 per cent, 
and the phosphorus and sulphur below 0.04 per cent. These two latter 
elements, however, seldom reach 0.035 per cent, and a phosphorus con- 
tent that is below 0.02 per cent is often obtained. The commercial 
stock is manufactured in two grades, one of which contains between 
0.20 and 0.40 per cent of chromium, and the other between 0.40 and 
0.70 per cent. Both of these can be obtained in any of the following 
carbon percentages: 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45 and 0.50 per 
cent. Another brand that is used to a large extent for leaf springs, 
and also for other purposes, contains from 0.90 to 1.50 per cent of car- 
bon and between 0.20 and 0.40 per cent of manganese, which is in 
accordance with the spring steel specifications of the Pennsylvania 



NATURAL ALLOY STEEL 



39 



Railroad Co. Titanium, vanadium and other purifying materials can 
be added to the steel if it is so desired, and thus further enhance the 
physical properties. 

These natural alloy steels are carefully made by the open-hearth 
process and are, in the heat-treated condition, in every way the equal 
to 31/^ per cent nickel steel. In some ways they are superior to this 
steel and especially is this true of the grade that contains the higher 
percentages of chromium, or when they are manufactured into parts 
that have a comparatively large sectional area. They are also cheaper 



DRAWING TEMPERATURES IN DEGREES FAHRENHEIT 


70 
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1 60 
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ir 

3o 

njo35 

1 ^ 

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tr 

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TENSILE STRENGTH AND ELASTIC LIMIT IN 
THOUSANDS OF POUNDS PER SQUARE INCH 


























































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NATURAL ALLOY STEE 




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CARBON STEEL MOC 


hinery 1 



Fig. 13. Comparison of Characteristics of Natural Alloy, Nickel 
and Carbon Steels 

than the nickel steels made by the same process, and in the billet form 
they are but little higher in price than the ordinary carbon steels. The 
high-grade and high-priced nickel-chromium steels are the only ones 
that are superior to the natural alloy steels in static strength, and this 
is largely due to the fact that they are usually made by the crucible 
process and contain a higher percentage of chromium, this being ap- 
proximately 1.00 and 1.50 per cent in the two best brands. 



Properties of Natural Alloy Steels 

For comparing the static strength, a large number of tests were 
made with natural alloy, nickel and carbon steels that contained 0.40 
per cent of carbon and were hardened at the critical point and then 
drawn at various temperatures between 500 and 1500 degrees F. The 
average results obtained from these three kinds of steels are shown 



40 



No. 118— ALLOY STEELS 



in Fig. 13. The steels compared all contained 0.40 per cent carbon. 
The natural alloy steel was quenched at 1520 degrees F.; the Zy^ per 
Gent nickel steel at 1500 degrees F.; and the carbon steel at 1530 
degrees F. The average strength of each steel at a given drawing 
temperature can be obtained by following downward the line indicat- 
ing the desired number of degrees, until it meets the curve of the 
tensile strength, elastic limit, elongation or contraction, according to 
which is to be found, and from this point following the horizontal 
line to the left, where the number of pounds per square inch, or the 
percentage, is recorded. In Table XII are shown the average elastic 
limit and ultimate strength as ascertained in some torsional tests 
made at the Pennsylvania State College. All heat-treated specimens 
were hardened and drawn to develop the best properties for driving 
shafts, axles, etc. 



TABLE XII. AVERAGE FIBER STRESS IN POUNDS PER SQUARE INCH 
TORSIONAL TESTS MADE AT PENNSYLVANIA STATE COLLEGE 



Kind of Steel 


Natural 
Alloy 
Steel 


3V2 Per 

Cent Nickel 

Steel 


Carbon 
Steel 


Annealed 


Elastic limit 
Ultimate strength 


41,500 
93,400 


40,800 

78,200 


32,500 
75,100 


Heat-treated 


Elastic limit 
Ultimate strength 


93,600 
130,200 


76,400 
108,000 


60,500 

102,400 

Machinery 



Much care has to be taken in manufacturing the ordinary nickel or 
nickel-chromium steels to prevent either of these elements from segre- 
gating in the bath or when teeming it into ingots. This is largely due 
to the fact that the nickel and chromium are additions and the bath 
must be heated to a comparatively high temperature just before teem- 
ing. In the natural alloy steel, however, the nickel and chromium are 
alloyed in the ore and are present in the bath from the time the melt- 
ing operation starts until the finished steel is poured into ingots. 
Hence the bath does not have to be heated to any higher temperature 
at the time of tapping than do ordinary steels, and any tendency 
towards segregation is largely overcome. Thus, the elements are more 
uniformly distributed throughout the mass, and a homogeneous metal 
is obtained. When such elements segregate and the steel is rolled, 
they produce laminations in the metal which have a very injurious 
effect upon its strength, especially at right angles to the direction in 
which they are rolled. 

Influence of Chromium 

The extreme hardness produced by chromium makes it necessary to 
use comparatively small percentages in steels that are to be machined. 
When the chromium content reaches 2.00 per cent, the steel is very 
difficult to cut when cold, and when higher percentages are used, the 



NATURAL ALLOY STEEL 41 

steel cannot be cut with any kind of cutting tools and must be ground 
to shape, this latter being an expensive method to pursue. Thus, in 
the high-grade nickel-chromium steels that are to be manufactured into 
parts of machines or instruments, the chromium content is usually 
about or below 1.50 per cent. Owing to the diflaculty of working even 
this steel, however, many grades of steel have been made with a 
chromium content of 0.25, 0.50 and 0.75 per cent, and it is as a substi- 
tute for these grades that natural alloy steel can be used. 

In steel, chromium gives the metal a hardness similar to that given 
by carbon, but to a lesser degree for the same percentage. It is a hard- 
ness, however, that makes the cohesion of the molecules much greater 
and thus greatly increases the static and dynamic properties. 
Chromium also greatly retards the formation of any grain or fiber, 
and thus makes the steel practically grainless. All of these effects of 
chromium upon steel cause it to increase its tensile strength, elastic 
limit, hardness, resistance to torsion, shocks, vibrations, or other 
stresses, and also increase its wearing quantities and prolong its life. 

Influence of Nickel 

Nickel increases the ductility, toughness and resiliency of steel, and 
also increases its susceptibility to heat-treatment. It reduces the size 
of the crystalline structure and tends to prevent microscopic cracks 
that are liable to develop into larger cracks and produce ruptures. It 
was first added to steel to overcome the property of "sudden rupture" 
which is inherent in all carbon steels. It reduces the tendency of 
steels to become damaged by overheating in hardening, and shows its 
effect in the hardening operations by making the tensile strength and 
elastic limit two and three times that of the untreated, or annealed 
steel. Nickel raises the elastic ratio in steels, i. e., the elastic limit 
is raised to a higher percentage of the tensile strength. This con- 
dition is always sought for in the better grades of steel. 

The two elements mentioned, therefore, greatly enhance the value 
of natural alloy steel for the various parts of machinery that are sub- 
jected to severe stresses. This steel also resists corrosion much better 
than other steels, the sulphuric acid test showing that it corrodes 
from 10 to 20 per cent less than the low carbon and manganese, basic 
and open-hearth metals with nearly all of the impurities removed, 
which have been given such names as "pure ingot iron," "old-fashioned 
iron," "toncan metal," etc. While there are some that doubt whether 
this test agrees with the results obtained from exposure to actual 
weather conditions, it is generally conceded that steels containing 
nickel corrode less rapidly than carbon steels and wrought iron. 

Working- Alloy Steels 

Natural alloy steel can be hammered, rolled, drop-forged, pressed, 
stamped, or machined with the same ease and at the same tempera- 
tures as carbon steel; no special precautions are necessary. The 
high-grade nickel-chromium steel (on the other hand, must be heated to 



42 



No. 118— ALLOY STEELS 



a white heat before being hammered, rolled, or drop-forged. The high 
temperature must also be maintained during the mechanical work- 
ing, and if it falls very much, the steel must be reheated. Nickel 
steels must also be carefully handled when thus working them, and 
hence it will be seen that natural alloy steel is more cheaply worked 
into shape than other alloy steels. Natural alloy steel is similar to 





TABLE XIII. EFFECT OF HEAT-TREATMENI 


ON FORGINGS OF 




NATURAL ALLOY STEELS 










Heated to 1550° F. 


and Quenched 1 






in Water 


1 


1 

g 


Annealed 






1 


Tempered at 1050° F. 1 


Pounds per Sq. Inch 


Per Cent 


Pounds per Sq. Inch 


Per Cent 1 






^ 


p. 






g 


JH 


1 


11 


11 


1 


1 

6 








1 


0.30 


89,500 


57,500 


28.0 


51.9 


106,500 


76,000 


21.0 


51.9 


0.40 


88,500 


56,000 


29.0 


51.9 


112,500 


83,000 


23.0 


59.8 


0.50 


119,500 


68,000 


18.0 


37.1 


135,000 


107,000 


16.5 


46.2 


1 

6 

1 


Heated to 1550° F. an 


d Quenched in Water 






Tempered at 1000° F. 


Tempered at 


600° F. 




Pounds per Sq. Inch 


Per Cent 


Pounds per Sq. Inch 


Per Cent 1 






g 


p3 






g 


g 




If 




1 
§ 


s 


II 


.2 4. 

11 


1 
c 
.2 


a 








H 


6 


M 




W 


6 


0.30 


131,000 


114,000 


17.5 


51.9 


193,000 


177,000 


8.5 


30.7 


0.40 


130,500 


118,500 


18.5 


51.9 


209,000 


188,000 


10.5 


37.1 


0.50 


155,000 


138,500 


14.0 


43.0 


252,000 


232,000 


7.0 


24.0 



other alloy steels, however, in that it is very difficult to weld by or- 
dinary methods; parts that are to be submitted to great strains should 
not be welded together. Like other alloy steels it can be welded with 
more or less success by the various electric welding processes and 
machines that are on the market. The electric machines that squeeze 
the parts together are preferable, as these prevent the grain from be- 
coming coarse, as it does when other methods are used. If the steel 
is hammered after welding, this will aid in refining the grain that 
has become coarse at the weld. By careful workmanship with the 



NATURAL ALLOY STEEL 43 

electric process it is often possible to obtain from 70 to 80 per cent 
efficiency at the weld, whereas an efficiency of between 30 and 40 per 
cent is all that can be obtained by ordinary welding methods. 

Natural alloy steels, like all other steels, will attain the highest 
strength only when properly heat-treated. In the untreated or annealed 
state, they show a tensile strength and elastic limit that is from 8000 
to 10,000 pounds per square inch higher than carbon steels of the 
same carbon content, but when properly heat-treated they compare 
favorably with other alloy steels. Some figures that were obtained 
from annealed and heat-treated forgings are given in Table XIII. 

Heat Treatment 

The heat-treatment is practically the same as that given other steels. 
The hardening temperature may vary somewhat, but not to any great 
extent. The brands containing from 0.15 to 0.20 per cent carbon 
should be heated to 1500 degrees F. and quenched in brine to obtain 
the best results. Those with a carbon content between 0.30 and 0.50 
per cent should be heated to 1550 degrees F. They can then be 
quenched in water as readily as carbon steels, although oil and special 
liquid compositions can be used for the quenching bath with equally 
good results. The temperature at which they are afterwards drawn, 
of course, varies with the kind of work that th.e finished piece would 
be called upon to perform. 

When hardening steel, a cold piece should never be put in a highly 
heated furnace, as it is liable to crack. It should either be preheated 
to above 600 degrees F., or it should be put in a cold furnace and 
heated up slowly. It should soak in the heat at the hardening tem- 
perature long enough for the piece to heat clear to its center. The 
work should never lie directly on the hearth of the furnace, but should 
be raised sufficiently to allow the heat to attack it from all sides, and 
it should be supported in a way that will not allow it to sag, as hot 
steel is soft and pliable and likely to bend. The axis of the piece 
should be vertical when plunging it into the quenching bath to pre- 
vent unequal contraction in cooling. The work should never have 
sharp grooves, corners, or other features, that easily develop cracks 
when the steel is heated and quenched. 

In drawing steel, a furnace should never be used that is hotter than 
the drawing temperature. It is diflEicult to judge the temperature 
that the work has attained in such a furnace and get within 50 degrees 
of the desired results. If the piece attains too high a temperature, 
it will be softer than that required, and if the drawing is too low, it 
will not be soft enough. With a tempering furnace held at the correct 
temperature, the work can be allowed to remain in it until it has 
absorbed the heat of the furnace and then accurate results can be 
obtained. A difference of 50 degrees in the drawing temperature is 
of much more importance than 50 degrees in the hardening tempera- 
ture, and is more difficult to estimate. 



44 



No. 118— ALLOY STEELS 



Casehardeningr 
Carbonizing or casehardening can be performed in any of the vari- 
ous ways that are now used for other steels. Pieces can be heated to 
a red heat and quenched in cyanide to give them a depth of case- 
hardened surface of a few hundredths of an inch; or they can be 
packed in iron boxes with bone and charcoal, or other carbonizing ma- 
terials, and then heated in furnaces for a time that is sufficient to give 
them a greater depth of penetration. "Where the output would war- 
rant it, however, the special furnaces that have been designed for car- 
bonizing with gas would probably give the most uniform results, if the 



HEATED TO 1580 DEGREES F. AND QUENCHED IN WATER. 
THEN DRAWN TO THESE TENfPEflATURES: 


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HARDNESS brinell 34S 320 297 276 257 236 217 194 173 150 

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Fig. 14. Physical Properties of 0.20 Per Cent Carbon Natural Alloy Steal 

work is properly done. This is also the cheaper method when large 
quantities are worked or handled. 

In any case, however, the carbonizing mixtures should not contain 
over 15 per cent of moisture or 0.50 per cent sulphur. Moisture might 
cause a pitting of the steel which is liable to cause it to chip on the 
surface, while the sulphur soaks into the casehardened shell to a 
considerable extent. A carbonizing temperature of from 1750 to 1800 
degrees F. can be used, and this will probably give the most rapid 
absorption and most uniform composition of the case. The time the 
steel is submitted to this temperature depends upon the depth of car- 
bonized case desired. 

After carbonizing, the work should be allowed to cool slowly until it 
becomes black in daylight. It should then be reheated to 1500 degrees 
F. and quenched in either oil or water. After this it should again be 



NATURAL ALLOY STEEL 



45 



reheated to 1350 degrees F. and again quenched in either oil or water. 
This double quenching gives much better results on all steels than 
does the ordinary practice of quenching directly from the carbonizing 
furnace and reheating but once to about 1375 degrees P. and quenching 
in oil. 

In casehardened work, the core of the piece has a carbon content 
of about 0.20 per cent while the carbonized shell contains about 1.00 
per cent. Thus, there are two steels of a different nature and these 
should be given different heat-treatments. In the double quenching. 



HEATED TO 1550 DEGREES F. ANDQUENCHED IN WATER. 
THEN DRAWN TO THESE TEMPERATURES: 


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HARDNEbb BRiNELL 377 354 328 293 268 246 225 202 134 1G5 

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Fig. 15. Physical Properties of 0.30 Per Cent Carbon Natural Alloy Steel 

the first heating and quenching hardens the core but overheats the 
case and makes it brittle. The second reheating restores the case to 
its fine-grain structure and also toughens the core, and the final 
quenching hardens the case. 

Uses of Natural Alloy Steels 

Natural alloy steels are largely used in the manufacture of auto- 
mobile parts. A grade containing 0.15 per cent of carbon is often 
used for carbonized parts where the toughness of the core is of more 
importance than the strength of the steel or its ability to resist 
shocks. When parts are required to withstand severe shocks or strains 
and have a good wearing surface, steel containing 0.20 per cent of car- 
bon is used. This grade responds more readily to heat-treatment. 
Thus speed-change gears, differential gears, drive gears, etc., are 
made from this steel. It is used without carbonizing where consider- 



46 



No. 118— ALLOY STEELS 



able toughness is required rather than strength, as in various struc- 
tural parts. It is also used for cold rolling or cold pressing, and for 
such work as seamless tubes, small drop forgings, etc. 

Tensile Streng-th, Elastic Limit, etc. 

The tensile strength, elastic limit, elongation and contraction of this 
steel, as affected by various heat-treatment temperatures, are shown in 
Fig. 14. The vertical lines show the drawing temperatures which are 
marked in degrees at the top, while the horizontal lines represent the 
tensile strength and elastic limit and the percentage of elongation and 
contraction. Below the chart are given the hardness scales of the 



HEATED TO 1520 DEGREES F.AND QUENCHED IN WATER 
THEN DRAWN AT THESE TEMPERATURES 


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TENSILE STRENGTH AND ELASTIC LIMIT IN 
THOUSANDS OF POUNDS PER SQUARE INCH 

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^.=,,.„.»o SHORE 65 02 60 57 53 50 48 44 39 36 33 
HARDNESS brinELL 437 410 *> 380 3i4 3157> 2'JO 200 235 207 109 189 



Fig. 16. Physical Properties of 0.40 Per Cent Carbon Natural Alloy Steel 

steels, at these temperatures, taken from both the Shore and Brinell 
instruments. The cold-bend testing properties at the various tem- 
peratures are illustrated by the sketches below the chart. 

From this diagram the heat-treatment that should be given this 
steel to obtain any of the properties that are within its range, can 
readily be ascertained. Thus if an elastic limit of 144,000 pounds per 
square inch, with a contraction of 31 per cent, is desired, the vertical 
line will show that the drawing temperature should be 700 degrees 
F. This would also give a tensile strength of about 177,000 pounds per 
square inch, and an elongation of about 6.5 per cent. The diagrams 
are based on 7/8-inch round stock; if larger pieces are used, the 
drawing temperature should be lowered. 

The grade of steel containing 0.25 per cent carbon is usually em- 
ployed for such parts as can be cold pressed, for instance, brake drums. 



NATURAL ALLOY STEEL 47 

frame members, axle housings, etc. These parts require all the 
strength that can be obtained in combination with enough toughness 
to withstand the operation of bending into shape without developing 
cracks or checks. Steel 1^4 inch round, of this grade, when made 
into bolts, has a tensile strength of 106,000 pounds per square inch, 
an elastic limit of 87,500 pounds, an elongation of 26 per cent, and 
a contraction of 69.5 per cent. 

The grade containing 0.30 per cent carbon is still harder and more 
applicable to heat-treated parts. Hence it is made into axles, connect- 
ing-rods, jack-shafts, drive shafts, and other parts that require con- 
siderable strength and at the same time a high degree of toughness. 
It is also used for drop-forgings, heavy forgings and numerous other 
things. The strength, hardness and cold bending properties of the 0.30 
per cent natural alloy steels are shown in Fig. 15. That still greater 
strength can be obtained than shown in this chart was proved by a 
test made by one of the automobile manufacturers. The test bar was 
properly hardened and drawn at 600 degrees F.; the tensile strength 
was found to be 236,000 pounds per square inch, the elastic limit, 
215,000 pounds, the elongation in two inches, 10.8 per cent, and the 
contraction, 36 per cent. 

The grades containing 0.35 and 0.40 per cent carbon are used for 
spindles, rear axles, crankshafts, etc. From the 0.40 per cent grade 
are also made locomotive driving axles and heavy automobile truck 
axles, connecting-rods, piston-rods, steering knuckles, etc. The proper- 
ties of the 0.40 per cent carbon grades are shown in Fig. 16. Some 
finished crankshafts, 2i/^ inches in diameter of the 0.35 per cent grade, 
had a tensile strength of 148,400 pounds per square inch, an elastic 
limit of 127,300 pounds, an elongation in two inches of 15.3 per cent, 
and a contraction of 53.8 per cent. 

The 0.45 and 0.50 per cent carbon grades are used where extreme 
strength is needed in combination with considerable ductility. Thus, 
transmission gears that are to be heat-treated without carbonizing are 
usually made from this brand. The strength when heat-treated will, 
of course, be greater than shown in Fig. 16, but the ductility will be 
reduced. 

At the present time there seems to be a tendency to "load" steels 
with alloying materials, and thus make them difficult to forge, weld, 
machine, or heat-treat; the results obtained do not always warrant 
the high prices of the finished parts. This natural alloy steel, how- 
ever, is not overloaded with such alloying materials, but at the same 
time has properties that are well within the specifications for which 
many manufacturers are using much more expensive steels. 



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No. 72. Pumps, Condensers, Steam and Water 
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Locomotive Building. — Cylinders and 
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Locomotive Building. — Valve Motion. 

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No. 34. Care and Repair of Dynamos and Motors. 

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No. 


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No. 


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No. 


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